Is there a way to transfer an existing slackware installation from a Desktop PC to a laptop?
Because the Desktop is more powerful, I am using it to try and build a minmal slack OS of less than 2GB-on the laptop compiling and installing pkgs I want would take much longer.
If I can't copy the existing system to USB and then to the laptop-what other way is there?

So you are compiling packages from source on the faster machine, and now you want to move the packages over to the slower machine?

It sounds like the best option would be to build with Slackbuilds so you will have installable binary packages. Then just install those on the laptop once you have Slackware on it. Make sure both machines are clean installs though, or else you might run into some dependency trouble.

Actually-no what I want to do is somehow completely replicate the already existing system on the PC and transfer the already installed system to the laptop.
I could just remove and add pkgs to the 3 install CD's-but this would be time consuming and arduous.
To clarify-I have installed a base system with only xfce4 and a few apps, no games, all libraries, etc. I then installed src2pkg and sbopkg. Then I installed some pkgs via src2pkg, deb2pkg, and sbopkg.
So now I have my complete installed system I want-and it went fast because I did it on the Desktop PC (1GB RAM AMD Athlon64 3300+ 2.4Ghz).
The laptop has 160MB RAM/4GB HD.
Now, I want to transfer the working system from the PC to the Laptop.
Obviously I could do a regular install to the laptop, then install everything I want-but as I said this would be time-consuming-but more importantly is that I can work out all the bugs on the PC much easier-
As an example-in trying to slim down slackware install I might accidently remove the wrong things-resulting in a "broken" system.
If that happens on the laptop I might have to repeat the whole install unless I knew exactly what I had done wrong-so again very time consuming.
As I already said-compiling pkgs from source, etc would take 2-3 times as long on the laptop.
Another big issue is whether or not there will be a conflict because the PC is a different ARCH than the laptop-so this all might be in vain??
Can I install a "generic" system to the PC-as in a "no arch" system that can be installed/transferred to any computer?
Thanks

"PC is a different ARCH than the laptop" -What do you mean? What is the arch of each machine.

You can pretty easily duplicate a running system simply by cd'ing into the root / of the running box and then copying everything over to another mounted partition or any directory you like:
cd /
cp -avx (list of dirs) /path/to/new
The trick is you need to exclude some of the main dirs on your system, like /proc, /sys, /mnt, /media, /tmp and /dev
These should all be created manually in the /path/to/new/
/dev needs a bit of special handling, because when slack boots up, /dev contains real device nodes which are part of the devs package. But, early during init, /dev/gets mounted on tmpfs so the underlying dev files 'disappear'.
But, you can simply use 'ROOT=/path/to/new installpkg devs*.tgz' to recreate the normal setup.
You can manually create the above dirs which are excluded from the copy operation, or use the same installpkg trick above to install the aaa_base package in the new root. Actually, you should use upgradepkg --reinstall instead of installpkg.
There used to be a HOWTO for doing this which was part of the 'zipslack' installation. I've done these kinds of 'installs' a bunch of times so I know it works. Bear in mind that you may need to edit the fstab file for the new machine if the root device doesn't show up the same. Also, you'll be copying over lots of stuff in /var which is not really necessary -but it shouldn't cause any problems either.

The desktop is a HP Pavillion AMD Athlon64 3300+ 2.4Ghz 1GB RAM, the laptop is a Toshiba 7000CT with a pentium 2 266Mhz 160MB RAM.
I believe the desktop is either a i486 or i686?
I don't know what the laptop arch is-anybody know?

As far as Slackware is concerned, they are both i686 so it's fine. You might have to reinstall some of the packages you've built yourself

OK-if they are of the same basic arch-can I install pkgs to the laptop that were built on the PC?
Like say I wanna build a pkg from sbopkg on the PC, can I also install that pkg to the laptop and it will work correctly?
If I build the pkg on the laptop it will take alot longer to build and the fan will be zinging!

You can indeed do that. I do it all the time. I have three PCs on my network, a desktop, a headless "server", & a laptop. I have a "recovery" partition (approx. 2G, CL only) on all three machines that I can boot into if I goof up the main partition. I use rsync to keep them the same, & a small script to select the proper HOSTNAME, fstab, hosts, exports & /boot/grub/menu.lst files. I don't copy a partition when it is mounted, so don't worry about copying /dev, /proc, /tmp, etc. I just copy them all. I also use sbopkg to build most of my packages on the desktop, then install them to the laptop.
Regards,
Bill

Depends on the CFLAGS, CXXFLAGS you use. By default they should use the arch of the distro (correct me, if I'm wrong (I always specify march)) you're building the software on. Because Slackware uses -march=i486 it should work on your Pentium II CPU, which is i686. However, if you would use -march=i686 or -march=native (with recent gcc), your packages most often won't work on older than Pentium II CPUs. I highly doubt that general info posted at slackware.com is relevant (-mcpu=i686) because -mcpu is deprecated for x86. You could use -mtune=i686 instead or just go with -march=i686 or
-march=native.

Assuming that both machines have ethernet cards in them, you could use NFS. Add the file systems you want to share to /etc/exports, allow access with /etc/hosts.allow and then start rc.rpc and rc.nfs. Then you could start your laptop off of your slackware install cd, and mount the shared nfs partitions. Then mount the laptop's filesystem (standard is to mount it in /mnt) and copy your files from your mounted nfs filesystem to your mounted laptop file system. Then bind /proc and /sys to /mnt/proc and /mnt/sys, and chroot into your mounted laptop file system to make sure it is working, and to set your root password. You should check the /etc/fstab and /etc/lilo and rerun lilo.