.11n is better than b/g, but .11n is probably not stable as it still new and still being tested. If you would like to invest your money on the .11n product than you would have the latest wireless LAN so you won't have to worry about having to buy it later.
The 802.11n is the new specification for home wireless LAN, and will be replacing 802.11b/g later on.
Yea, I've had heard a lot of bad comments about Belkin routers, I own one myself but never ran into any problem except for the time zone kept resetting itself, I just turn that thing into a switch.
The IEEE won't approve of the standard until around 2007, you'll start to see a lot of 802.11n product being sold, that's when you start buying it once everyone else have tested it.
That 3com look reliable to me, they are a good company and kind of like the underdog compare to Cisco but I've had the privilege to work with both product and can't decide which one is better. Though 3com is cheaper compare to Cisco, which Linksys is a division of.
Dlink and Netgear are also great manufactures. Though I can't be bias because every product has their own bad comments about them.
SRX (suppose to increase wireless performace and speed) using MIMO technology. If you believe it will improve your wireless performace, it's up to you. I have no personal information to tell you if the technology actually works or not. I really don't know much about this MIMO thing at this point.