that's a good deal. things to watch out for on those:
-screen is crap. total ****ing crap. it's so bad you're going to come up with excuses NOT to use it. but it works and displays pixels so if you aren't picky should be fine
-RAM ceiling is 1.5 GB
-HD is a super weird size, 1.8 but... horizontal. as in not like the old iPod hard drives. and they are slow. you can get SSDs in that formfactor on eBay but I haven't tried it. There's also an addtronics CF to IDE card that will fit (but only one out there, thinkwiki has the model).
Honestly the x40 IS pretty dated but they are really fun machines and they're well-supported under linux. I recently picked up an x61s to replace my x40 which has a dying screen and the difference is astounding. Same formfactor but it's actually a relatively 'modern' computer with a C2D. They run for about 200 so if you just want a super cheap basics-only machine the x40 will do you fine
i would recommend picking up a flush-mount battery so it doesnt have the 'growth' sticking out -- amazon has them for 30 bucks or so. you can also get neoprene black and red sleeves on ebay for about 10 bucks.
