300114 PHP forum field modified

need the php script modifed that works this page: [login to view URL] In the lower right corner where you enter the payment amount, I need it not to allow them to add a $ sign in the field blank. It is messing up my payments when they enter the amount say for example $10.00 verus 10.00. I need them to only be able to submit the information with 10.00. make $ a illegal character! Need this like asap. Fixin to have alot of payments hit that page in about 2 hours =( Shane