Memory performance
While it doesn't define system performance, memory bandwidth can play an important role, particularly with integrated graphics platforms that must share bandwidth with an onboard GPU.

Thanks to the Athlon II's on-die memory controller, the 785G configs have much higher memory bandwidth and much lower access latencies than the G41 Express. The difference between the two 785G setups isn't as striking as one might expect given the 800MHz gap in memory clock speed, though.

The following graphs are a little indulgent, but they paint the latency picture in three dimensions, across multiple block and step sizes. I've arranged the graphs in order of highest latency to lowest. Yellow represents L1 cache, light orange is L2, and dark orange is main memory.

Yup, the 785G access latencies are impressively low, even with pedestrian DDR2.

Application performance
WorldBench usually fills in as our application test suite for chipsets and motherboards, but it doesn't get along with Windows 7. Instead, we've used a small collection of application tests that cover three of the most demanding tasks encountered by modern PCs: video encoding, file compression and decompression, and image processing.

The 785G configs have meaningful edge over the G41 Express in the first pass of our x264 encoding test. And as one might expect, the DDR3 785G config is also faster than the DDR2 setup, although not by much.

Our x264 benchmark doesn't take advantage of the potential general-purpose computing power housed within the Radeon HD 4200's stream processors, so the results above are more a test of CPU and memory performance. We've yet to see applications designed to leverage GPU power for video transcoding match the output quality of traditional encoding software, though. GPU-accelerated transcoding currently seems more appropriate for converting video for playback at low resolutions on handheld devices.

Memory bandwidth plays more of a role in 7-Zip compression than it does with decompression. In both cases, however, the 785G system outruns the G41 rig.

The tables turn when we stitch together a four-photo panorama shot of Damage Labs. Here the G41 system performs the stitch operation a few seconds faster than the quickest 785G config.