Well shoot, upgrading rarely works well even for power users unless you're upgrading very often instead of only when necessary. By the time your CPU can't keep up, Intel has a new socket and you need a new motherboard. By the time your video card needs replaced, you'll likely need a new PSU to handle the new power requirements. RAM changes slow enough that you might get two or three upgrade cycles from your RAM, but you'll likely need more... and if you bought 4x1 GB and now you want 16GB, you're throwing it all away anyway. Hard drives are the only things that are easy enough to replace every day, but hard drive tech doesn't move that fast. Upgrade to even a slow SSD and you're golden for quite a while.

I bought my computer five years ago. After two years, the only things original were the hard drive, the RAM, and the case. After four years, only the case was original (and even that's trashed now as pieces and parts have broken).