Our ex (?) friend can remotely access our computer. (We did not authorize he just helped himself to the priveledge on the pretext of helping my husband with eBay purchases.

What can we do? Can he access our personal computer information, i.e. on line credit purchases?

How do we disarm him from our computer?

It really depends on what he is using for access.
Best to have a look through the Add/Remove list and uninstall ANYTHING that mentions remote access.

Most importantly change all your passwords.

These instructions are for XP Pro, if you have the home version or Vista they will differ.

Right click on the My Computer icon and select properties.
Click the Remote tab.
Uncheck the checkbox under Remote Assistance and uncheck the box under Remote Desktop.
Under Remote Desktop click the Select Remote Users button and remove any names that appear in there. If there is a name in there for an account that you did not create make a note of it. You'll need to delete or at least disable that account. I recommend the latter at first to make sure you don't delete something unnecessarily.

Do this next step with caution. If you disable the wrong account you may have some serious problems with Windows.
Open the control panel and go into User Accounts, click the Advanced tab and then click the Advanced button.
Select the users folder and look at the logins... if any names jump out at you as being a login that he would have created then double click on it and check the disabled box. If there is a guest account, make sure you disable that. If you are not sure then don't change it.

As Curlyben suggested check the Add/Remove programs and look for things like VNC, PC Anywhere, Remote PC or GotoMyPC.

It might have been a one time thing where your husband e-mailed him a request for assistance. But it would depend on how he did it and hos you have your system setup as to what he can access.

Wow, I want to thank everyone for this prompt advice! You never know what some people are thinking especially when this person is sometimes unpredicatible. Especially since he was a user on our computer and would just sit here using our computer for hours most days. He could also access our computer remotely to check our business transactions.

He may not be that malicious, but I always like to be prepared for the worst.