wanting to clean up my credit in order to purchase a house

I am wanting to clean up my credit in order to purchase a house. I especially don't want to have to pay a high interest rate. I have several delinquent credit cards on my record but it's all over 2 years. I have plans to pay all bad dept off in another year. But I read from your web site after 2 years even if the dept is paid, it wouldn't raise the fico score very much. In spite of the bad credit reported, I do have 2 current credit accounts that are excellent which are on my recent file.

My question is ... would I do better by leaving the 2 year old bad dept unpaid? I'm afraid if I paid the bad dept off, it wouldn't reflect on my credit report as paid. I don't trust any collection agency's promises unless it's in writing. And I have had collection agencies refuse to put any negotiation in writing. At least, I was smart enough not to take their word at face value. I didn't pay the agency.

Also, can I dispute the amount I am being charged to only the credit bureaus and bypass the collection agency all together? There are stock piles of late fees and late charges that I feel I shouldn't have to pay. For example: In reality, I may owe only $600.00 but after the late charges from the creditor and fees from the collection agency, my dept increases to $1000.00. Is this even legal?
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the original creditor is the only place to negotiate
collectors cannot sue or threat to sue
and they can not put sold collections on your report in MOST cases

valdiate these debts
and call file with your state attorney general is they do not compy which they can't
most collections were sold for pennies on the dollar to help the first creditor.
it is illegal for them to threat to sue and to put it on your credit report
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Will 2 year old bad dept affect your fico score, especially when you have good credit that's been paid on time and has existed over two years?
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i dont know
what is your credit report fico score at all three bureaus?
what does it need to be?
many times a home or car loan will require one to have all past due outstanding debts paid in full.