56K tweaks[edit]
For those of you that are using WinXP, go to Start, Control Panel, Internet Options, Connections tab. You will see Add, Remove, and Settings button. Click settings and then go to properties towards the bottom. When it comes up you will see your modem at the top, click the Configure button right underneath it. In the drop down box set it to the highest setting, not the default 115200. Uncheck the modem error control box and hit OK. For some reason mine unchecks modem compression too but thats ok, compression is still enabled in the Phone & Modem properties anyway.
OK, so what this does is eliminate retransmission of data which is the cause of the lag or "warping effect" that dialup users experience due to your modem having to resend a request for data that is lost. Hence, it just goes right on with the data it has and you don't end up on the far side of the map then back again.
If for some reason you can't connect to your ISP, set the setting back to 115200, but mine lets me connect.
Note: may not work for everyone depending on what settings your Dialup server has with error control but I have pings of 120-130 and no warping effects with this setup.
Originally copied from: http://forum.americasarmy.com/viewtopic.php?t=62071
Also try this tweak guide from TweakTown: AA TweakTown Guide