I should say a big round of applause to 45CAT then. I am doing my 45's at mo, what you do is log your 45 collection on there ("I own") and then add the records not already listed. You can now dowload the result, straight into Excel and even more impressive I realised I could transfer that excel file to my blackberry, so I can refer to my collection when I'm out and about.! (you can also do the same for WANTS)
a really handy resource and its free.
"not more records! Where are you going to put them!"