It all depends on what model of Netgear router you have. Does it support 802.11n?
The new BT Home Hub uses the latest 802.11n protocol, which theoretically will be faster and have greater wireless range than the previous 802.11g. But your broadband connection is possibly going to be a significant factor in the speed of data transmission.
You say that you're "supposed to get 8Mb", but you'll probably notice that the your contract will say "up to 8Mb". Depending on your distance from the telephone exchange (I presume we're talking about an ADSL broadband connection?), you might be getting a great deal less than this. In which case, changing your router might do very little to increase the speed of your up- or downloading.
Have you run a broadband speed test? If not, click on the Broadband Advisor link under the "Topic Zones" heading on the left of this page. Run a test and see what your true speed is (at that moment - remember that it'll vary considerably throughout the day/week/month... etc).