Vista - Router not giving me what it says it will

I just bought a belkin router and it says its suppose to give me 108 Mbps of data transfer but when i checked on my laptop it says that i am only getting 54 Mbps what am I doing wrong why am i not receiving 108 Mbps of data transfer. How can I get it up to 108 Mbps?

I have Comcast High Speed Internet (Triple Play)

And this is my router: Belkin - Wireless-G+ Wireless Router with 4-Port Switch - F5D9231-4

Those are theoretical maximums for 802.11g (54Mbps) and the not-really-a-standard-but-good-marketing 802.11g+ (108Mbps). Since your internet link is likely to be a fraction of that, the distinction between G/G+ is utterly academic unless you're doing lots and lots of LAN transfers between two or more of your machines on that network.

also your laptop wireless receiver is most likely only 802.11g , so no matter how fast your router can do LAN transfers its limited to how fast you can receive them