For whatever reason, I can't get Parallels to work with most hotel internet systems (be they wired or wireless). Works fine on my home wireless system (with WPA) and my friend's wireless network (with WEP), but it just plain refuses to work on the road.

So I use BootCamp as well. Also, Parallels really can't handle 3D windows apps (like games), so BC works better for that, as well. I dropped a 100GB HDD in my MacBook so even with two 5GB Windows installs, space is not an issue.

One thing I like about Parallels is that it works with your Mac's folders, so I don't need to duplicate my dataset (like you have to with BC). So I mostly work in Parallels and only revert to BC when network connectivity is not possible.

1GB is fine for Parallels if you don't run many apps at one time in either OS (I dedicate 512MB to XP and 512MB to OSX). If you do, then you want 2GB so each OS can have 1GB to play with.