There is nothing preventing you from
trying linux. However, I feel you may be disappointed, since getting Windows programs to run under Linux either costs money or is EXTREMELY - PRETY DANG hard. Sorry, but that's jsut how it is for now.
If you still want to try, then I'll answer your questions. No, it's quite easy to install (even in expert mode, which I reccomend doing so you can select ReiserFS as your / filesystem. All you really need to know is how linux's file system is set up. Instead of having the top level be the drives themselves (as in Windows, like C: D: E

, the top level for Linux is / , or root. Everything is under root. Now how linux sets up the other drives besides the / drive is by mounting them as directories. Like /drive2 would be a different drive than /usr or such. Usually you do not have easch directory as it's own drive (of course) unless you happened to be running sonme sort of supercomputer. It souds hard, but don't worry, it's quite easy.
You CAN still use MSOffice and Warcraft III, but its difficult at best to get them to work. Your best bet is a program called WineX (or Wine if you want to drop Warcraft III). It emulates Windows with DirectX 8, so you can play some nice games (no DX9 yet, since WINE uses OpenGL and OpenGL ver 1.5 (the version with shader support) is still being tested). Ask if you wish to attempt to use the program.
For SOffice, you can get a replacement that works very similarly (and even reads/writes Office files) is a program Called OpenOffice, that comes with Mandrake.
AIM has a native version for Linux at
www.aim.com . Just click Get Aim>Linux. A clone of AIM called GAIM (that is more powerful since It can do MSN and Yahoo as well) comes with Mandrake, so you'll be okay there anyway.
If you decide to switch, good luck! You can also install Windows later and dual-boot the two, so that you have the optiopn of selecting which one to run at startup.