Regardless of what you think the reasons for not supporting IE9 are, the facts are XP doesn't support it. If that's important to your business you need to upgrade.
I upgraded because the XP box I was using wasn't up to the demands I had of it. Eclipse was slow then upgrading to [recent] MS Office was the final nail in its coffin.
Once I'd turned off Win7's more obnoxious graphics I actually like it. It's a tiny bit crashy but much better than XP. Updates are handled automatically and it does get out of the way and let me get on with my job (and commenting on these fora).