I am a believer of the Dave Ramsey teachings and am currently doing his 'Total Money Makeover' plan.
In his book he says that you don't need to buy on credit and pay it off to build your credit score in order to get a good rate on a home loan. He says that it is yet another money myth that many people have become to believe as true. You can probably google it, but if you aren't finding anything I can quote the page from his book where he talks about it...in short he says that if you've had the same job for 2 years, don't have much debt, and have a good mortgage broker you can get a good interest rate. www.daveramsey.com
btw - we recently bought our first home. We got a great (4.75 fixed @ 30 years) interest rate and we hadn't used our credit card for a good 10-12 months prior to getting the loan approved.
(Message edited by jetskiprosx on February 25, 2010)