Windows 7 should run in just one gig of ram (whereby "should" I mean I actually have run it in 384mb.) If you're just running a single diagnostic tool, then a gig should be fine. In fact, it's said that Windows 8 does even better with low clock speeds and memory situations than 7, but I haven't taken a bunch of time to really compare this on netbook or old ThinkPad hardware. (Which I call out specifically simply because that's what I have on hand.)

Likewise, if you're just running a single diagnostic tool, it should be fine without a network connection if the slight improvement in XP's responsiveness on that hardware is more worthwhile than networking.

Anyway, let us know how it goes. Netbooks can be good single-purpose computers. The one I have, which is an eeePC 901HA (Atom N270, 1gb/160gb) I usually use attached to the back of a monitor as a sort of thin client.