I dont know what it is about MSN AdCenter, but I found it to be a rip off compared to others (Google, Overture). The $100 Voucher came in handy, however they continued to charge me for the service prior to using the voucher. Once I'd spent around $300 from my own pocket, the voucher began being used but at around tripple the cost per click. Has anyone else had this issue?
I think the voucher and the tripling of your cost-per-click are totally 2 different incidents which may have happened coincidently.