If you have AT&T DSL, they have a speed check utility that comes as part of the software bundle. I found several things about DSL that might help, first run a direct line from the DSL modem to your house telephone junction box. AT&T doesn't tell you but there will be about a 25 to 30% speed drop if you just plug into a wall jack. Mainly this is because of the filters, if any, and telephones especially wireless phone base stations that cause unseen interference. Additionally if you have DSL or any other service, only use the fastest speed available, otherwise the routers will make your signals wait while others go through. This is a simplification but basically you get what you pay for. Until a few months ago I had Cox and their 8Mb speed service and ran AT&T 6Mb DSL side by side and it was faster by about 20% or so in downloads and page loading.
There is something else, if you have a router, wireless for a laptop and the firewall is activated than turn off the XP desktop firewall since it is not needed and will cause huge speed drops with incoming packets.