I have quite a similar setup here. Although my Slackware 10.2 install was the second one I tried. Because you're a desktop user (like most of us I guess), I'd simply put 100-200MB aside for swap (more than enough RAM there anyway) and give the rest to / since you'll never know how you'll be using the space and don't want to end up swapping files around on partitions for nothing.
If the installation freezes while uncompressing the kernel, your BIOS might not be up to the job for booting off the CD-ROM -- in that case you should get the files needed for a bootdisk and rootdisks from the offical Slackware ftp servers, since none are included on CD1 (since 10.2 methinks). Of course you can also get them from CD3 if you downloaded that. You can easily create them in Windows, just follow the guidelines on slackware.org.
Without them, I would have been lost on my old PI 200MHz box
Also, another word of warning/advice: you might not be able to get X (or any GUI for that matter) running at all. For me there have been two problems: an ATI Graphics Pro Turbo PCI card (sound familiar?), which Slackware couldn't detect and before that a really ancient, braindead 15" monitor that even Knoppix couldn't handle (after a fit of rage, it now rests in pieces