For what you want, I'd definitely go with linux. If you're prepared to put in a bit of time learning a new system (note 'new', not 'more difficult'), then the rewards could be great. The only disadvantages would be a lack of games (it's getting better but linux gaming is still WAY behind windows in terms of choice), and maybe video editing (things like Adobe premier etc). Video encoding is a different kettle of fish, and a few customized mencoder or ffmpeg scripts will run rings around any Windows software for dvd ripping and generation. I wrote a script about a year ago to rip my DVD collection. I got the 'time infront of the PC'' down to 3 minutes per disc. I managed to do all my 150 odd discs in a (very long and boring) day.
You may as well give it a try, since:
- It's free
- You can dual boot anyway if you want
- Don't like it? Just delete it.
As for the server related stuff, then imho, linux wins hands down. Everything you'll need is free (as in properly free, not 'obtainable'), and it's more secure/reliable. And for surfing the net, at least for now there's no (or pitifully few) linux viruses, so no need for anti virus/spyware or any onf the countless other 'security' programs people install on windows.