Wifi Vs Lan

If i download a test file from servints test server [url]
1, Using my laptop on wifi (54g) I get average 177Kbps
2, Using Lan cable on laptop i get over 600Kbps

Router is Netgear dg834g
Location UK

I tried this on another location diff adsl lines with seperate computers and routers lan and wifi, the same results

How can this be, I know there are some overheads to using wifi over lan

I removed all WEP,WPA etc.. prior to tests