Two comments about the sp_OACreate method -

1) VBScript doesn't support many regex features that are standard in Perl (lookbehind, atomic grouping, possessive quantifiers, \A, \Z, etc.) 

2) sp_OACreate can cause memory leaks:

http://support.microsoft.com/kb/897572

http://support.microsoft.com/kb/816937/EN-US/

Make sure you have SP 4 installed and that sp_Destroy is getting called every time if you use this method.  I've seen it shut down production servers on a daily basis.