My system startup had slowed so I installed a Gigabyte Silent 256MB 8600GT recovered from a failed system. Startup is 1 minute faster w/o having to reinstall Vista on an Intel DG45ID. I get 1.4 improvement in both graphics performance scores although graphics drops from 1.26GB to 256MB. The business graphics has already been very useful although I wasn't looking for speedup. I left the BIOS on autodetect for graphics rather than disable the onboard graphics on Device Manager. This should be less problematic for system and driver changes. I get a second Intel startup screen however and I am being very cautious. Should I have disabled the onboard graphics? Intel documentation seems to suggest otherwise. This has DirectX10 and shader 4.0 support. The upgraded failed 965WH system (also Vista) now closely matches the DG45ID system but its startup has not slowed.
I'm now sure the slowup was caused by installation of a newer all operating system LAN driver. The Vista32 specific driver is much smaller and must load quicker on startup.