The sad state of home computing

I have this computer, watertown. It's about three and a half years old now. Has a reasonable keyboard, two sufficiently nice CRT monitors. And I never really use it any more. Some of this is actual problem: the fan in the power supply is sufficiently noisy that I don't really want to wake anyone up with it, and it's kind of annoying to actually have running because of that. (And consequently it's not a good remote-login machine either.) But other things are just "the machine is old": I didn't think a 700 MHz Athlon would be too slow, but the desktop clearly underperforms my newer laptop (everett) on "things that take CPU power to render", like Gnucash (!) and Microsoft Train Simulator. Also, watertown's 20 GB disk, partitioned between Debian and Windows 98, just doesn't have the contiguous space anywhere for a reasonable Vorbis file collection.

Conclusion: Moore's Law hits, watertown takes ten damage in the usability department. This feels distressing to me, though I can't really describe why. For a few hundred dollars I could put in a new motherboard with a faster processor and extra storage, but is this worthwhile if I'll just use the laptop for everything?