Just for the hell of it, I'd recommend a E4xxx or E5xxx series, just to get the dual core and additional cache. If your needs for that box increase, or you want to start running some server-side apps/etc, you'll have a little more power to play with. The new Celerons aren't too bad either, but is there really much of a price difference? Probably pick up something decent for dirt cheap here in the forums actually.
edit, whoops, forgot the new cellys are dual core
what the hell, the Celeron E3200 and above seem pretty decent, scratch what I said.
