The WRT600N got rave reviews for throughput in PCMAG. I also noted that all "Vista Certified" routers must be dual-band!
I may be buying one myself if wiring my current WAP directly to the VMC box doesn't fix my identical issue.
Deane G Vista SP1 Home Premium 32 w/Pack, 2x A180, 550 Pro, HD4350 at 1080i to plasma, Intel D945GNTLR w/Pentium D 2.80GHz, 2GB, Seagate 300MB + Hitachi 1TB, Linksys DMA2100, Harmony 550, TMT