I have tried many tweaks on my 800 (see sig below) and can loop 3DMark2000, play UT for hours, and just about anything else at 982MHz. I thought it was totally stable until I decided to run Prime95. To run that, I have to gear down to 956MHz., so I guess 982 is not 100% stable like I thought it was. Can't really tell any difference between the two, it is still fast

Anyway, I can boot and run Windows at a Gig, but crash in 3DMark2000, and UT will not run for long. I am keeping it at 982 anyway, until something that I use on regular basis crashes, which it has not after running a week 24/7 using my business software and playing games. I guess that what has been said about the green core 800's maxing out at 950 or a little better is true. My T-Bird never exceeds 40 degrees Cel. and idles in the low 30's, so I know it is not a cooling thing, and I have played with every possible multiplier/FSB adjustment.
EDIT: I guess it really is not bad at all considering the lowest Pricewatch prices today on Retail Box T-Birds:
800MHz.....$190.00
850MHz.....$256.00
900MHz.....$274.00
950MHz.....$376.00
1000MHz....$460.00 (OEM, no Retail Boxes listed)