I think alot of people are asking the same question.
Myself I am going to wait untill Windows Vista and DX 10 are relased.
Ditto. I have yet to install FSX but will do so shortly, and then only to test some addon projects and tweak them for suitability in the new sim. and in addition to this, and until an affordable and appropriate hardware upgrade is available, I'll focus on gathering up all required addons and tweaks, and putting everything together gradually, so that it will be a simple matter of plugging it all in when the time comes. In the meantime, any regular flying will still be done in FS9.
It's natural to want to try out the latest version; the curiosity factor can't be denied. Waiting until better-optimized hardware is available, at a reasonable price, makes sense - am not saying no-one should be flying in FSX now, just set any expectations of it accordingly.