Personally i dont think the encryption would drop you down to 8mbps, as already recommended above;
- Check the channels of neighbouring wireless networks, then use one that isnt being used.
- Remove all G devices from the network (while you test) this should give you an indication if this is effecting your speeds.
- Home setup is always an issue, but a rule of thumb would be to place the router as centrally in the house as possible, staying away from outside walls, router antennas are omni-directional. Note that it should also be kept away from the floor and metal objects (e.g. filing cabinets)
http://www.microsoft.com/athome/setup/wirelesstips.aspx
http://gadgets.softpedia.com/news/Wh...er-119-01.html