When i tried wow for 10 days, i had a 6200 also, 256 agp and my fps hung around 50s 60s
At 1024x768 with max settings, and your getting sub 20s with low settings you say?
I see you have a 1.7ghz p4, i think that may be your cause, as you have 1gb
ram which is fine, and the graphics card is fine.
I think its down to your processor.
Also how much space is free on your main harddrive