On my page How to dual boot Linux and XP I don't quite explain or where to install Linux, so I thought I would sit down and try to give a brief overview of things to consider when you install and OS. For instance I never mentioned how much of the hard drive do I give each partition, some for each os ya know, or some for a fat32 partition.
If you have an OS (Winodws,Linux,...) on your system already and no room to make a new partition you have a few choices.
This is the easiest way to do most installs. You don't have to mess with your primary drive and the program and storage space you may want remains intact. Though you will have to make some changes any way you decide to go.
I've used Partition Magic 6 and 7. I used 6 on Windows 98, and 7 on Windows NT Workstation and Windows 2000 Pro. It was easy to resize my partion to make room for a new partition. Though there are some other applpications out there, but I have not used them.
If you have Win9x you can install NT,Win2k, and Xp on the same partition, just say so in the install.Be carefull here, when you install Windows on the same partion as another Windows you may overwright some directories and file, example PROGRAMS, so you may want to watch what you do. Do a full install and leave the filesystem intact. This will work if you install on a fat32 partition. If you have NT,Win2k you can install on the NTFS partion as many installs as you like. Same with XP. I installed it a couple of times on the same drive just to play, as I said becareful.