There is only one cure... TIME. I used to have the upgrade urge all the time, but after 10+ years of first building and constantly upgrading my pc, the main urge is gone. Last major upgrade(mb,cpu,ram,video) was november 99.
I have only added ram,hd, and video, and even that was spread out over 6 months, and was finished six months ago. My pc still runs everything I play ok, so I do not feel the need to upgrade it. Wait, I forgot about the digital camera, scanner, and printer I bought last november for my newest hobby. I guess I did upgrade afterall, just not the usual stuff.