It's best to get 802.11g now.
1. it costs quite comparitively to the slower 802.11b; so you might as well fork over a couple extra dollars for a lot of possible gain. At the very least, you get generally better than 802.11b speeds regardless.
2. it works GREAT, and very fast, if you're just starting out and are buying 802.11g access cards along with it.
3. Linksys, at least as far as companies, said they will provide an upgrade to the final spec for all its current 802.11g customers.