If you're doing detailed selection for a build of your own, you might want to hit the PC Mag Extreme Tech Build It page. The first article shown there is a DIY (Do It Yourself) on " The DIY $1000 Athlon XP Gaming Rig" (March 30, 2004) that used the Athlon XP 3000+.The article does have some performance results on the rig they built with this processor.
From the "Build It" page, there are several other links to similar configurations, including a couple that do "side by side" AMD and Intel comparisons.
Note that "which processor is better" is meaningless unless you specify the whole package in which you're using it. Motherboard and other related parts are critical in any comparison.