Well apart from upgrading your Speeds VIA your ISP try this :
WINDOWS XP INTERNET TWEAK: Now this step will enable you to change the Internet Bandwidth limit in windows to make surfing the web just that little faster. First of all go to ''Run'' and then type ''gpedit.msc''. Once you have done that locate the ''LOCAL COMPUTER POLICY'' branch and expand it, Then under that locate the ''ADMINISTRATIVE TEMPLATES'' branch and expand that also. Then under that locate the ''NETWORK'' branch and expand that also. Then under that locate ''QOS PACKET SCHEDULER'' and highlight it in the left window, Then in the right window locate ''LIMIT RESERVABLE BANDWITH SETTING'' and double click on it and then on the settings box check the ''Enable Item'' and where it says ''Bandwidth limit %'' change it to 0.