We've been using dog old Dell GX260's for checkin with no problems (P4, 2GHz, 256MB ram) ... even the slowest netbook today will run laps around our GX260's :-)
Guess the biggest issue I see is the small keyboards and screens on the netbooks ... if you're ok with that you're golden. That and make sure the OS is not vista. XP and Win7 run great on netbooks, but vista not so much.
We're actually beginning to phase out the GX260's with HP thin clients running XP embedded OS. In our multisite location this has worked beyond my expectations. Since the OS and F1 app are embedded there's nothing to troubleshoot at the OS level since it's locked in flash memory. If a reboot doesn't fix an issue it's either hardware or networking. Makes our troubleshooting doc much easier for volunteers to follow by reducing many steps :-) Downside is updating the F1 app, but luckily that doesn't happen too often.
Jason