This is for broad band connections, though it might work for dial up.
•Make sure your logged on as actually "Administrator".
•Start->Run->type gpedit.msc
•Expand the "Local Computer Policy" branch.

•Expand the "Administrative Templates" branch.
•Expand the "Network Branch".
•Highlight the "QoS Packet Scheduler" in left window.
•In right window double-click the "Limit Reservable Bandwidth" setting.
•On setting tab check the "Enabled" item.
•Where it says "Bandwidth limit %" change it to read 0.
Effect is immediate on some systems, some need to re-boot. This is more of a "counter
what XP does" thing. In other words, programs can request up to 20% of the bandwidth be
reserved for them, even with QoS disabled.