Yes my idea you could run a print server and have access to floppy drives,cdrom, and cdburner if you wanted
yes linux does some messenger services, not sure about yahoo.
OpenOffice is cross platform compatible and works quite well
PDF files are handled by linux just fine, as are postscript
There are a few games for linux, but nearly the selection windoze has.Highend, right now, armyops and doom3 is only ones I know of off the top of my head.There are probably another 20-30 other games available though.
game controllers, there's a few that work, mostly logitech
As a general rule if you want to play games stick with windoze and deal with that mess, video drivers and buggy code are constant problems with windows games in my experience, especially microsoft games.What few linux games Ive tried have been very very good and stable, no problems or crashes.
If your going to do this you will need to spend some time learning how to use linux, it takes some time to learn.Otherwise stay with windows and deal with the extra expenses involved.
The areas linux does really well in are business applications, networking, video-DVD,editing,playback,ripping, etc etc and automating just about anything.Its also the most popular in the server market.