I struggled with the same question before going with Uverse; I was planning on using my wireless N router within the uverse network, since it was a wireless G, and not "N"
Once it was hooked up, my wireless speeds were VIRTUALLY IDENTICAL to to my wired speed,(I have the new 18 Meg download speed), so I didn't bother using it, and sold it on Ebay!
As cab driver said, since "G" supports speeds up to 54 MBPS, the Uverse Gateway should be fine for quite awhile..