Hi... I have a linux-computer that i cant user because i dont have a cpu-fan for it at the moment, but i need some files that are on the hard-drive. Can i just place the harddrive in my other computer running XP, and copy the files, or do i need some other program to read the files?

of course, XP wil never be able to see the Linux partition (Micro$oft will NEVER allow that), but there is some application that will allow you to read your Linux partition.
If you Linux partition filesystem is Ext2 or Ext3 (which is the usual) you could try "explore2fs". It will allow you to perform basic operation, like copy/paste but don't expect much speed.

Do you have access to a Fat32 formatted partition? For example a USB drive, or a fat32 partition on your windows computer?

If you do, you could boot the windows computer with Knoppix or another live linux distribution, and then copy the files from the new drive you added to the fat32 (VFAT) partition. Since Linux doesn't write to NTFS, things get a bit more complicated. If the Windows computer you are talking about is running Windows 98 or Windows ME, then there wouldn't be a problem transferring the files the the 'My Documents' directory on the Windows partition.

Another option would be to boot up the computer with Knoppix and send the files to a third computer via the network.

Explore2FS is available at: http://uranus.it.swin.edu.au/~jn/linux/explore2fs.htm
however I find that my windows xp system freezes when I try to use it, an alternative is to use Ext2IFS by the same author ( http://uranus.it.swin.edu.au/~jn/linux/ext2ifs.htm ) which is a driver allowing windows to understand linux disks and access them with a normal drive letter.