You need to up the clock cycles that DOSBox uses (CTRL+F12, try 10500-10800) and you may also want to up the frames that it is allowed to skip (CTRL+F8, frameskip = 7 or 8).
Bethesda is providing a free download of Elder Scrolls: Arena (one of the largest RPGs in computer history) of their website as a 10th Anniversary gift. You'll have to download DOSBox to get it to run under XP or 2000.
http://www.elderscrolls.com/downloads/downloads_games.htm