Lizardking--

I use the exact same technique to get those scores up-- it is amazing how much difference it makes.

One caveat though-- be careful not to pay TOO much and end up with a credit-- I have found that Experian, especially, chokes on credit balances and
reports them as debt.

Paying before the bill cycles is a pain, but it is definitely worth it if you are going for a big loan.

Another tip, for several months prior to applying, you might only want to use cards that accurately report each month. I love Citibank, but their reporting S#ck$. Once I got them to (finally) report my correct balances, I put the cards up temporarily.
They sometimes take months to report, and then they get it wrong anyhow.

Cheers--
C