Hi there,
In the current climate, and according to alot of chat I had with the credit agencies for me fixing my rating, and looking in financial advice websites, it's currently true. just to point out, I did mention 'any accounts that are NOT needed'. To add to this, look through your report and look for any old or non used accounts you've held - these may be such things as credit and store cards, but also covers things such as old internet service providers, old mobile phone number accounts with one of the companies, old loans you've paid back. The bit of information you are looking for is the status - you currently want as many accounts listed on your report as 'Settled'
As I'd built up an excellent rating over the last 15 years or so, I was 'thrown' credit cards through the post with automatic clearance and 5 figure credit limits and I took about 4 extra that I hardly ever used over the years. When I did have my rating lowered due to a reason I know about, I talked to the people at Experian at good length. My plan was to use say £30-50 per month on the card and ensure I paid it in full back each month without fail. However, in order to 'build up' my ratings, I was told that having those cards with high availablity of credit was probably detrimental, as the lenders are now thinking about people using up their credit and not being able to pay it back and thus adding to the crazy debt/borrowing mess the country is in. By implicitly calling up your credit card providers and reducing say a £7500 credit limit to say £4000, 'currently' the credit agencies and potential lenders are viewing this as a 'responsible' individual for lending purposes. Hence, the credit reference agencies are increasing credit scores.
Now the USA credit agencies might not be working in the same way, and may still be increasing ratings based on having an old account - I think it's best calling a USA credit rating agency and asking them directly to see their response and/or visiting USA centric debt and finance management websites and resources to read the US ways of currently doing things.
Of course, if you have a really old account that is indeed still in use and has never been defaulted on etc, then of course keep it ! I haven't got my current credit report in front of me right now, but I seem to recall that the rating system used goes back as far as one, two or 3 late payments as a initial history. It does show when the account was opened as well, so that'll show right away a length of 'credit history'. So, theoretically, you may have had an account for 10 years and never ever defaulted for 9.5 of those years. If you then (for whatever reason) miss, 1 or 2, or 3 payments, you're credit score will be diminished and the lenders will not really look back over the last 10 years or so, they'll see the recent history as it'll give them a good idea of your potential to actually pay them back.
Lastly, the basic credit rating booster things you can do are very well known and doscumented in credit reference agency websites, and on websites such as MoneySavingExpert etc etc. It always makes sense to get your 'own' particular credit rating report and make changes that are relevant to you.
Hope this helps
Cheers! Dennis! West London & Slough UK!