First of All: Nice Job TJay.

I too built a similar system using linked servers in order to monitor failed jobs, backup history/backups out of date tollerance, databases::applications::servers, space issues at the file level, etc. What I've moved onto in SQL 2005 is a similar system, with the same Reporting Services reports as I was using prior (and practically the same schema) using SSIS. You can populate a table with your server/instance names and so long as you keep that up to date as you bring new instances online you're good-to-go. It was based in-part off of an article in SQL Server Magazine in May or June of 2007 on SSIS. It runs seamless against my 80+ instances and 800+ databases with much less overhead than my old linked server solution. I've only had it fail once, but that was due to an instance being down for maintenance. With a little more work on the customized logging that would have been apparent however.