Yech. WRT54G2 still not supported by DD-WRT nearly an year after release. And with it's crappy 2MB Flash and 8MB RAM will only support micro version if that support ever comes. Wouldn't touch this one with a 10ft pole.
If you want a good router get the Linksys WRT54GL with 5% off coupon at Buy.com for $50.34 shipped. It's a no brainer for the extra $2-3.
I bought the wrt-110 (internal antenna, looks like the one linked in the OP) since I happened to brick my wrt-54g. I got 1/3 the wireless speed with the 110.
I just changed to a WRT54GL with Tomato and couldn't be happier. I don't have experience with this router on sale, but I would recommend the WRT54GL if you need wireless. It is tried and true.