If I recall from the CR1/I-130 process - the cashed check would have a case number on the back - is it the same for this process? I tried to look on the back of my check, and couldn't tell if there was a case number. There was some cryptic number, but didn't look like a case number.

you will get a receipt number when you get your NOA...

I have heard that the number on the check won't work.....

I've had an SRC number on the back of my checks, but it doesn't work for the USCIS case status online system.

Yes, I tried it - didn't work. I'm impatient! Another related question - the TSC dates show they are dealing with I-751 cases from July 2006 - this doesn't seem to be true looking at processing times through VJ - or is it really taking that long?

Does anybody know what the first 3 letters of the receipt mean? I looked at the back of my check and it starts with WAC, but I don't know what they mean.

the first three letters signify the service center that is processing ur case. .....i can't remember what stands for what anymore - google it, or look on the boards. u fill an answer.

EAC is Vermont, that much I know. I would assume WAC is Nebraska, since that's where you filed, Mononoke.

Junglee, we have an EAC number written on the front of both of our checks. It doesn't do anything when we try to check it.

Then we got the blue receipt for the biometrics fee, and there is a different EAC number under case number which also doesn't work, then down where they check the box for what the receipt is for (biometrics), the same number from our cashed checks is there. But again, it still doesn't work.

From what I've read, we have to wait for the NOA1 to get the actual case number.

Yep, this is correct from my own experience. Only the case number in the actual NOA works.
I filed my I-751 to Vermont, and the case number on my NOA begins with EAC.