Yeah, after using it for a while, aside form those "vista needs your permission" popups, I don't have too many things to bitch about. the only real issue I've encountered is not being able to share files with XP (though it sees the samba share on my MyBook fine).
I find that Vista runs quite nicely on this machine, actually. It's not even all that good, when it comes to hardware (2GB DDR2, and an AMD Athlon64 X2 QL-60). Getting Vista64 on a 64 processor would likely run even better than this does, being able to take advantage of the 64bit registers.
Not to mention that XP is rather rapidly becoming obsolete. Very soon new games are going to stop making versions that don't work in DX9 and only work in DX10, forcing people to upgrade if they want to play new games. And god knows what microsoft will do to force people to upgrade soon, once they've completely stopped selling XP and stopped offering those "pre-downgraded" versions and such as well.
And, since it's software, not hardware, you don't have the issue of early adoption like you do with hardware (you know, getting the first video card released in a series that turns out to be much shittier than the next batch, despite still being marginally better tan the current popular generation, and costing an arm and a leg).
(yes, I actually made an intelligent contribution to the thread)