mayn, if you lookin to upgrade ya internet speed - look at it from a price vs performance perspective and whether you need the extra speed.
jus changed from 3 Mbps/256 Kbps to 7 / 800... and a I notice a huge difference, and it only cost $5 more.
as for routers... pick somethin that does at least 54 mbps, although you will notice a slight performance decrease (as compared to 100 Mbps wired connection) which is kind of obvious due to interference and a slower protocol. 108 and 125 mbps routers are pretty, I have myself a 108 mbps buffalo wireless router and it runs beautiful, has a long range too.