I'm on XP at work and have multiple IEs installed.
Everything besides dedicated mobile sites I still make sure things looks alright in iE7+. About 35% of our audience is still using IE7. Hard to argue with numbers. Probably should point out that I work for a company that owns several small, medium and large newspapers around the US. So we are talking several enterprise level sites with millions of hits each month.
I think it is a bit wee premature to be dropping IE7 – IE8. I understand why the decision was made but don't really agree with it on a practical level. Than again the people behind jQuery can pretty much do whatever they want and us developers will just figuratively have to take it up the @ss. They know it and we know it. Power hungry individuals who think they can *change things but in all reality they are probably going to just make things worst for those who have to deal with practical problems, not a fantasy world. Inevitable there will be a point where people only use the most recent version. Hopefully those developing open source projects realize it will be important to use the one that still back-ports to legacy IE. IE7 is really far from dead and IE8… probably no where near dead. At least not based on numbers I have seen and we have pretty sophisticated tracking tools for our slew of sites.