SATA performance
I used HDTach for these benchmarks. They're largely intended to find a problem with throughput, CPU utilization, or both. I used HDTach's 8MB zone size setting for all tests. The hard drive was a Seagate Barracuda V with SATA interface.

The Radeon Xpress 200 passes with flying colors. The Intel 900-series chipset have slightly higher burst rates and write speeds, but the Xpress 200 is comparable to the VIA and not far behind the Intels.

ATA performance
These tests are HDTach again, but with a Seagate Barracuda V with ATA/100 interface.

Again, no major problems, although the ATI's CPU utilization is a little higher than everybody else's.