The iPad 2 is the best of course but the iPad 1 is by no means outdated. It will get full support, updates and so forth, for a long time yet.
The iPad 2 has the same screen resolution so no worries there. The biggest differences to me is the iPad 2 has a faster processor but if you never use the iPad 2 you won't notice anything, the iPad 1 is mighty quick. The weight and thickness is not THAT much difference but again it'll only seem like a big deal if you only use the 1.
Price! The refurb iPad 1's, for the 16 gig wi-fi, only are running $349 I think. Or close to that. The refurbs have the same warranty as new, has a new battery and outer casing which is all that matters.
You can only get a refurb by ordering it from the Apple website and the availability comes and goes but it shouldn't be a long wait to get one.
I just looked and they have them right now...
http://store.apple.com/us/browse/home/specialdeals/ipad/wi_fi ...but only the 32 and 64 GB. $429 and $529 which means when they have the 16's they will be $20 less than I said above at $329! A great deal!
Here are the +3G's...
http://store.apple.com/us/browse/home/specialdeals/ipad/wi_fi_3g