Okay, updates!
"Let 1k Windows Bloom" took 3 seconds. I was rather baffled by it until I got the results and realized what all those flickering windows were about!
This is with 512 MB of RAM, which is what the machine came to me with (and more than I've ever needed pre-OS-X, honestly… though sticking in 2 GB at some point does sound fun!). Virtual memory is off and I've already tweaked my extensions and such a fair bit—one of my favorite ways to streamline and/or customize! Maybe I should post a list at some point.
No sign of the ambient light sensor or keyboard backlight working, alas. I don't think I actually own any Firewire devices, so someone else will have to test that, sorry!