re: we haven't been on a rolling upgrade "cycle" for several years now?
No. IT budgets have been bludgeoned over the last 3 years. Resulting corporate spending for PC upgrades has been pushed out. There is a fair amount of "catch up" demand yet to be seen.
i know a few VERY large firms (couple are Fortune 100) that are doing huge firmwide PC replacements over the next year. IMO a lot of gear bought pre-Y2K is now fully depreciated and "obsolete"...but I aint no expert..