I've found XP's wireless config to be user-hostile, but almost universally workable. It doesn't really like letting you tweak and fine-tune, and you can't really get at its guts, but for 99% of APs I've used it with, it's worked fine on its own.
The corollary, of course, is that you're completely and utterly boned 1% of the time...
If you can use the wireless config built into XP, it's probably the simplest thing. There's a checkbox in your wireless config program that's labeled something like "Use this software to manage wireless connections". Turning that off should activate XP's built in mojo.