So, all these systems are not in the same physical place? You have to visit different sites to perform system upgrades? Are these actual physical upgrades (processors, cards, drives, etc.), OS upgrades, or a combination of the two? If they are physical upgrades, what happens to all the 'outdated' equipment? Do they then sell it to resellers or what? How many other colleagues do you have working with you to upgrade all these systems? It sounds like a lot of tedious work for just one man. How many hours a day does it take you to do all this? You must never rest!

Are you still adding more systems to the fold? When do you expect the return to level off?