be aware tho, the biggest flaw with the revolution is that there's usually a framerate drop (compared to say an audigy2, not sure how it performs in games with the live), not a riduculous drop tho...i'd say 3-10fps roughly. But sound quality-wise, it will spank the living hell out of out of the live!, i did the same exact upgrade. Since your budget is pretty hefty, I'm gonna recommend this as an all around rig:
M-Audio REVO: ~$100 shipped from newegg (out of stock, try other popular retailers like googlegear, or hell, just buy it from your local comp store)
Sony CD3000's: ~$400 (you could find these on ebay retailers easily at lower prices, otherwise audiocubes.com or this other store lou recommended when he bought his second)
META42: ~$200 (price varies depending on options. if you want a good performing meta at a low price, check out tigger's headsave.com).
Makes $700 nicely there, even shipped. If you play alot of games and 3D positioning counts (fps games, etc.), don't even bother with Grados. I personally feel they're strictly for music. The cd3k's however...oh my...huuuge soundstage, easy to pick out things left right back above below. It's built with extremely light materials and it's soooo comfortable (just get's your ears hot after a few hours).
edit: oh forgot to add, if you're completely new to this (ie. you weren't a lurker around here before) and are skeptical about the sony's (too many sony haters that think everything they make suck...well, everything they make TODAY sucks), do a search, plenty of posts. There's also PLENTY of threads on computer headphone recommendations as well.