I think you need to have the version 4.x or earlier WRT-54 models to re
flash the firmware and one of the third party firmwares. The newest
version 5.0 and up models have less RAM and flash memory and can't
support the linux based re flashes.

Generally, yes, it's better to have the 4.0 and earlier hardware versions.
Or get one of the new ones specifically noted as WRT54GL with L indicating
Linux. You can use a 'micro' version of the firmware on the new version 5
and later boxes. And for a simple shore-link and access point setup that's
actually sufficient.

I scoured fleabay for a couple of weeks and picked up several 4.0 and
earlier units just so I'd have spares.

Then there's also the new units from Buffalo. Check the
http://www.dd-wrt.com website to find out which models are supported.

-Bill Kearney