apple mac gets 3.5mbit...upstairs PCs 0.5mbit

hey folks this one is perplexing me...

we have BTBroadband connected to a 4000k profile and several PC's and an apple mac all connected wirelessly to a netgear dg834gt. just done a speedtest.net test to london server and get 3.5mbit speed from the apple mac.

come upstairs to the 2 windows PC's and each seems to get limited at 0.5-0.6mbit download?

any ideas what could be causing such an issue?

what are the wireless connection speeds on the adaptors, they could be as low as 1M. RWIN values on PCs (link in sig leads to tweak testing sites).

not sure of the apple mac but i'd assume its high. its closest to the router and has at least a G adapter in it.

this PC i'm currently on adjusts the speed anywhere from 11mbit to 46mbit. the other PC uses a dongle and tends to get 108mbit all the time

a 4th PC using a LAN cable also gets the fullish 3.5mbit download. i'm suspecting the wireless is just junk but i cant understand why it stubbornly bounces around at 600kbits on both PCs with wireless but can deal out the full speed over ethernet and to an apple mac with wireless.

turns out the wireless range just SUCKED majorly...

scrapped that and went back to wired which is far preferable. full speed on all devices now.