How to update Ultimate Doom

Hi everyone, I thought I'd get myself a copy of Ultimate Doom on ebay to warm up for Doom III, having not played Doom for years :). My question is what should I be downloading to get the best experience from it? I'm on XP and the game is running fine, but I'm curious to see if there's any mods to run it at higher resolutions or maybe have mouse look. I checked out the source ports part, but I'm not sure if that's what I'm needing.

Thanks in advance for any advice :)

Yes, source ports are what you want.
For playing Doom online: ZDaemon
For playing Doom with prettified graphics, mouselook, etc: jDoom
For playing Doom with XP support that is closest to the original experience: PrBoom
For playing Doom with mouselook, etc. without graphics prettified too much: ZDoom

Thanks a lot mate :). Cleared it up for me nicely.