What type of rent receipts do you use?

I am looking to stream line our billing system in 2012.

We currently use a spreadsheet for billing and a ledger card system with hand written receipts that are copied onto the ledger card for receipts- not effective at all. I am keeping the spreadsheet and looking for something I can print out from my PC and use special type of paper/stamp to make sure the receipts can’t be copied by tenants.

Currently when I add up the deposits I input them on a spreadsheet and total them up. So most of the work is completed.

I am thinking something along these lines:

TRAILER1 $350,00 RECEIVED1/3/2012Receipt # 10025 (sequential #) ----Some special stamp here with park name and phone

Any feedback or ideas?