How many baddies do you have on your report?
If you have unpaid collections, send them a PFD letter and don't pay them until they agree to delete the TL after you pay.
Send GW letters to all people you were late with and ask them if they will remove the lates from your report.
Get your utilization down to below 10%.
From what I am reading on the e-news and hearing on the news, it is becoming more and more difficult to get a mortgage with the current housing mess and subprime lenders. You may want to focus on bringing your scores up and saving for a good downpayment before jumping into the market. I am sure that is not what you wanted to hear but it is hard to get a mortgage these days with a score lower than 620 and I am hearing 640 is the new marking point.