Hacking problem

My IBS board keeps getting hacked and the support team think it may be due to my wordpress (which I host) Here is what they say:
It really does look like WordPress may be the culprit here that’s allowing them access. You may want to make sure that it’s up to date and possibly contact the creators to find out if there’s anything they can advise you to do to ensure this doesn’t happen again.
I do have the most updated version of wordpress 2.1.3 – I installed it myself as soon as it came out. Can anyone give me any advice on this please.