Well the 11Mb card is a clue already... remember that a lot of bandwidth goes to control packets, so your private Lan will consume a fair amount of that.... 50-75% is a little low already... so there are probably a fairly high packet loss % which MAJORLY affects any secure sites, and still affects the speed that other sites gets loaded at. (Secure sites will reload the whole section you are busy with, if it drops 1 packet, normal sites just have to stop and ask for a resend)
Please also note that the cards are measured in Mbps (Mega BITS per second, not Mega BYTES), so devide the Mbps by 8 and see the MBps (Bit is given in small b, Byte in capital B)
11Mbps = 11264 bps (Mega = 1024)
= 1408 Bps (1.375 MBps) ( you wont get a connection higher than 1MB with this)
54 Mbps = 6.75 MBps (You can espect a connection of about 5 MB)
108 Mbps = 13.5MBps (very similar to normal wired LAN - Normal LAN is 100Mbps)
THe highest speed Wireless i am aware of, is 108Mbps (routers and cards), which is
