I'm in this boat as well, my 6yo PC, while running strong and still performing 95% of what I need it to do well, I just don't like dealing with component failures.
My strategy is to always buy "the best that 3 grand will get" -- and normally this works out well, however, these days, 3 grand for a homebuilt PC buys a retardedly overbuilt assortment of gear, and is actually difficult to spend without going off of the deep end.
My main problem right now is that the SSD drives do not seem mature yet, and I don't fully trust them to go the 5yr distance. The whole windows7 trim support, and the DOA drive issues are a nuisance -- also in a raid0 config, they seem to be saturating the SATA bus, which isn't really an issue for me, but it's annoying in a general best-practice sense to me.
I also like what they're doing with water-cooling, but I don't trust that to last 5 years either.
I'm waiting until spring. If you game at all, the nvidia dx11 cards should be out too, ensuring video support for awhile.
If you were wondering, 3 grand these days buys:
2 x QuadCore HT Xeons (2.26ghz - baby nehalems)
either 12gb or 24gb ram (I forget which it was)
asus board
2 x 120gb SSD drives for boot
4 x 2tb caviar black drives for storage
2 video cards of choice (I have 6 monitors), PSU of choice, case of choice
and you still end up with like $600 left over.
$0.02.