I was able to find one example of a Windows Server 2008 installation where Control Panel | System and Maintenance | System showed that Service Pack 3 was installed (see the image posted by SC13Sonic in the spiceworks thread Has Anyone Seen a SP3 for Windows Server 2008 R2?) but the general consensus was that the incorrect Service Pack number was displayed because of a corrupted Windows registry entry.

Did you use Ex_Brit's ISO file to install Service Pack 1 and Service Pack 2 after reinstalling your Vista OS instead of downloading those service packs from the official Microsoft site and and applying them manually? Or were you attempting to repair a corrupted Vista SP2 installation with that ISO file? I'm not exactly clear from your post in that thread why you needed that ISO file or what you were planning to do it. I see you requested a Vista ISO file yesterday via a private message from Ex_Brit per post # 2,990 in the thread Vista ISO Download. I've never heard of an official Service Pack 3 (SP3) released for Vista (or Windows Server 2008).

Windows 7 aio service pack 2