You have seen lots of replies above--here's my 2 cents:

I don't recommend the apple airport express if you are a PC user because you need to install special software to configure it. I always found the software to be slightly flaky and had to fight it to find the airport express. I also hate having to install software on my computer for a special purpose like this.

Most brands of routers have a built in web server interface to configure--way better.

I have been having good luck with my d-link, but I think any 802.11 g router is fine.

I figure on switching to N when it goes mainstream in order to make my laptop backup faster.