How much faster is 802.11n compared to older standards ?

Theoretically, 802.11n can reach speeds of 600 Mbps, and even that assumes you're using wireless n's maximum four spatial streams.

For now, the Wi-Fi alliance will be testing products with three streams, putting the maximum at 450 Mbps.

By comparison, the old 802.11b/g standard reached 64 Mbps, and the wireless "a" maxed out at 11 Mbps, so wireless n is considerably faster.