2008 cold start 2 sec, warm start <0.5 sec
2010 cold start 14 sec (after full day of using computer with several hour long idle period, SuperFetch .. more like SuperFail), warm start 4 sec.
I wrote two rants about SuperFetch in 7 here but removed them after figuring you've heard them from me before.
If this site weren't purely about random hype vids these days I'd ask for a Going Deep on what went wrong in SuperFetch and what are they going to do about it while it's still somehow relevant. I don't think it's going to be relevant for long after everyone has large SSD but I find it hard to believe majority of Win7 is running on SSD systems so the timing of making it useless in 7 is really annoying.
edit: removed some comments about what RamMap shows after days use. It almost looks as if videos I'm copying with robocopy from net share are being cached (rather than something useful like those apps that take age to load) but not quite certain if I interpret it correctly.
VS 2010: With resharper enabled, it is a bit slow (14 seconds on a 10,000rpm raptor), but with it disabled, I'm getting a 2.5 second startup.
VS2008 start up mimics the same speeds as 2010
ReSharper for me is what causes VS to start up slow, and I'm cool with that since ReSharper lets me code faster.