John,
Looks good from over here. Good to see you're running RC5!!
First of all, first person shooters really steals those CPU cycles, so that will cut your score quite a bit. I do it all the time - no big deal. If you play Quake3, UT, CS or anything else like that it will bring down your keyrate, only when you're playing the game. It will only effect the keyrate of the cruncher you were working on during that period.
Same goes for OGL screen savers.. I had one called Maya Paint Effects, it brought my stats down terribly. Another very imporant thing to check is that your system isn't going off into standby mode. (Power Management CP -> Always on.. select your monitor to go off if you want...)
The best thing to do is to exit out of all applications in your system tray before you go to bed, but it isn't necessary by any means. I just leave the cow down there and that's it. 🙂 I prefer the "I'll launch it if I want to, don't do it for me" mentallity.
Lates, bro.
Tom