Linux not running well
 

On my computer I have a dual boot between Simply Mepis (with gnome) and windows xp professional.
I love using linux but it seems to run slower than xp eg, things take longer to load, frames dont draw fast, etc)

Im not sure that it is using the full capability of my hardware. Even though I have the nvidia driver loaded I dont think my gfx card is working correctly since screensaver movement seems to be low. This doesnt really make sense since my processor is a athlon 64 3200 @ 2.4Ghz and Gfx Nvidia v9999 128mb.

Does linux always run this slow on modern computers?

No, definitely not.
The graphics part sounds more like a Xorg issue than a problem with Linux. Have you read all the documentation on the nVidia homepage, and mainly the sections detailing the changes you need to make to your xorg.conf file?
Regarding the slow startup of programs: that may be related to the filesystem and mount options you are using. For example, I have found ext3 without any tweaking and default mount options to be rather slow. But after some tweaking, I find it to be quite fast. Just a thought.
Hope that helps.

Well, I am running here a Slackware 10.2 in a Pentium IV HT, 512MB RAM and an ATI Radeon 9550 256MB. The startup process really take a little more, maybe becuase Linux has to start many services, but it is only a little more. In the graphics part, it is pretty fast. Even faster than Windows, I think. BUT...I am not using KDE/Gnome. I haven't even installed them. Nothing personal against who uses, but I don't like. And here comes a stupid question, you did set your swap spacw right? If you did, try changing your wm (if you are using kde/gnome, of course). The others can look very "hard" and "empty" in the beginning, but see the screenshots that comes with their pages to see the wonderful things you can do if you write the right things in the config files. I personally use fluxbox and I am loving it. Hope it helped.

Thanks for trying to help everyone. I am still n00bish so I dnt always understand what u people mean :P

I set 1GB swap space, however I have 1GB of ram.
How do I tweak the file system?

You mentioned you had an Nvidia card, and without the drivers (and a proper xorg.conf setup) the GUI would indeed redraw slowly. So I would recommend you start there.
After that, you could look into turning off unused services to get the amount of background noise down.
Also make sure that DMA is turned on for your hard drive (try "hdparm /dev/hda" as root). Without DMA enabled, you are likely getting very low transfer rates (to see the actual numbers, try "hdparm -tT /dev/hda"). Of course, I am assuming hda is your hard drive.
Of course if you want to get drastic, recompiling your kernel (and trimming it down) tends to help a lot.

There are lots of advanced tricks you can try, it just depends on how in depth you want to go. But the two easiest and quickest fixes are ensuring Nvidia drivers are setup and DMA is enabled.