I was comming to ask more less the same question and saw this post.
I have the following:
+2gb corsair dhx
+1 HD SATAII
All this supported on a Antec TruePower II 480w.
My CPu is prime stable and the 8800gt is giving me 14283 3DMarks
Everything looks good, no crashes, games are...well..i guess normal (i used to play with a 1950pro, so everything looks better than tat!
But seeing your responses i wonder if i'm playing over the limit or i'm giving a hard work to my PSU.
Do you think i should upgrade, even when everything "looks fine"? i'm really a noob in what psu matters!
EDIT: BTW, i read the FAQ at the top here and is too much for me
i checked the "eXtreme Power Supply Calculator Lite v2.5" and is giving me a 392w but i never trust those calculators