An unsurpassed issue of strangeness has come up.

I have not even considered turning on my main computer for two weeks. The only other times this has happened was on vacation and when I randomly reject computers entirely during the summer.

I wouldn't have known it, but apparently I'm fully capable of doing all my computer-related stuff(cough cough, internet, games, chat, games, photo editing, and games) on a 630mhz Celeron.

Detailed analysis on several of the programs:

The GIMP:

Fully usable, though quite a bit of scrolling is required if you're working on images of any size. An SD card is especially useful here, though you probably have one if you're doing photo editing at all

Tremulous:

Inside ridiculously populated human base on 'Fastest' quality: 12fps

Inside ridiculously populated alien base on 'Fastest' quality: 14fps

Outside on 'Fastest' quality: 35-65fps, regardless of if there are people out or not.

Inside non-base areas on 'Fastest' quality: 45-65fps

All of these are very playable, even in the highly populated bases.

Need a mouse for any actual gaming though, the trackpad doesn't cut it.

Team Fortress(Darkplaces engine, low quality settings):

Average 35fps regardless of area.

Warzone 2100:

No idea of FPS numbers, but very playable, but with a bit of slowdown if FireFox is open.

Mupen64 with Zelda 64:

Pending results.