I had a 20" monitor a while back before I got my 24" and trust me, if I where you, I'd go with a 22" or higher. I mean for $30 more you can get a 22" on Newegg:
(both at $169.99 as of 3/29/09)
Venting Time: And yes, I know what people say about Newegg and there 8 dead pixel policy so I'll say it before someone else does.
Newegg's return policy is if you want to return a monitor that has dead pixels it has to be 8 or more. Now many people say they will never order a monitor from Newegg because of this but I myself think its worth the risk. I ordered my 24" acer from Newegg and not a single dead pixel. I had a couple friends say the same thing like: "What if you get 7 dead pixels? Then your screwed!" when I ordered my monitor. And from all the 240 review on my monitor, only a small handful even had 1 dead pixel. It was worth the risk at the time because this monitor was at such a great deal for such a big size.
So basically, if you want you want to order from Newegg, do your research on the monitor, read the reviews, open 100 reviews at a time and do a control + F and search: "dead pixel" on each page and see how many got a dead pixel or 2. If a monitor seems to have a lot of reviews saying "dead pixels" then don't go that route.