Yes, sidebanding is a good thing ;>)
Go to start/run and type SMARTGART. That brings up a test applet that will
check to see whether your motherboard prperly supports Fast Wrties (and a
bunch of other stuff.) It will automatically choose the ones that work best.
On my old Abit KT7A-RAID with a VIA chipset, SMARTGART disabled Fast Writes
even though it was turned on in the bios and passed the test. I could enable
it manually, and found that it worked fine at stock speeds but would lock up
3DMark 2001 when the fsb was overclocked even slightly (which also OCs the
AGP bus on the board.)
On my new Abit IC7 with an Intel chipset, SMARTGART enables Fast Writes and
I have no such problems, even though I'm using the same Radeon 9500, modded
to 9700 and clocked to Pro specs.
Basically every system is different, and SMARTGART is an attempt to
customize the settings to guarantee stability.