It won't affect the web surfing speed - that is between your router and your ISP only - but it may appear too if your WiFi is being heavily used by multiple users. Remember that wireless has a max transfer speed (
What is the actual real-life speed of wireless networks ? :: SG FAQ[
^] may help) which will be shared between all clients. So if you have WiFi at 100Mbps shared by 10 people all of whom want 15Mbps for high res video then some of them (likely all) are going to be unhappy. You are also going to have to have a very close look at your local server: HDD transfer speeds for my one-year old 16TB NAS work out at about 35MBps with just me, and you will likely be sharing that as well.