Yes, Liam is correct.
We have done this internally a month or two ago, Switched from EV7.5 2003 x86 to EV8.0 on 2008 x64.
It's pretty painless.
We did the upgrade first, and then just followed the move EV Server procedure found here:
http://seer.entsupport.symantec.com/docs/293911.htm
Keep in mind that all your registry settings for EV will be stored under the WOW64Node!
(HKLM\Software\WOW64Node\KVS)
This is a common pitfall ;)
Cheers