Users can see their credits in their postbits and profiles if you have set the option to yes in the vBulletin Options screen under vBCredits Global Settings.
If you have altered your postbits or profiles and would like to include the credits, the variables are $vbphrase['credits'] for the word, and for the value is $post['credits'] for posts, $userinfo['credits'] for profiles, and $vbulletin->userinfo['credits'] for the currently logged in user ($bbuserinfo['credits'] for templates).
Also, in the usercp is a link to Manage Credits under subscriptions, which links to credits.php, which also displays the number of credits and is also where the donation portion of the script is.
Edit:

no problem asw, I want this to work for you as much as you do.