Microsoft Exchange Server License downgrade

Hi Everyone. Im hoping I can get some information. We are a non for profit currently running Exchange 2003 server standard. We have reached our Database size limit of 75GB and are looking to upgrade to enterprise. I undertand that 2003 enterprise is no longer available for purcahse and as such we would need to purchase 2010 enterprise and then purcahse a downgrade to 2003. I am wondering if this is something that Donortec are able to offer along with the Exchange 2010 enterprise license available on the website. Thankyou, Regards, Shane