Almost all the consumer-level networking stuff out there is much of a muchness. Usually the same chipsets and board designs, usually the same firmware used as a starting point and customized to add the particular manufacturer's logo and so forth.
The differences seem to come in two places - design/materials for the enclosures and support (and by that I mean both customer support and upgrades to firmware). So which brand to go with depends on what you place most importance on.
Netgear's stuff is well made - almost everything comes in a nice blue painted metal case. It's got a solid feel. However, their tech support is virtually non-existent and they're usually last of all of the manufacturers to upgrade their firmware. This might change now that Netgear is entirely on their own (they were part owned by Bay Networks, or Nortel, or both, but bought them out) but it holds true at the moment.
Linksys stuff is, IMHO, generally cheap and plasticky in appearance. I also think much of it looks weird
I'd imagine the cost differences between metal cases and injection molded plastic would be one obvious place they sell for less. However, I also get the impression that their support is better. I don't know about customer support, but I *do* know that they've always been good about updating firmware to add new features in a timely manner.
When I move from 802.11b to .11g or .11a or telepathy or whatever the next thing is, I'll be ditching the Netgear stuff. There's nothing wrong with it - it works well - but the firmware for the ME102 AP hasn't been updated since January, even though there's been a more recent version available since late last year. Linksys' equivalent product has the most recent version of the firmware, and they've gone on to make their own improved version of the product with their own (superior) firmware.
Another way to find out - go to dslreports.com and look at the hardware specific forums for Linksys and the others. They usually give you a pretty good idea of what to expect.