Re: Lack of 32-bit Server platform
The real problem is if you have 16-bit Win95/DOS era software as that won't run on 64-bit Windows. OK you may also have driver problems as well for older hardware under 64-bit (remember how crappy 64-bit XP support was?). Sometimes it will run on Linux emulators (Wine, or dosemu, etc) but that is a significant gamble.
Now you might be saying "Who runs 16-bit any more?" without realising there is a lot of small speciality software from that era that works, and changing the software to a newer version is a major PITA for various reasons:
1) New software license costs
2) Maybe no longer compatible with old, special, and very expensive hardware
3) Different file formats so you cant read/write previous data
4) Different work-flow so you have to re-jig lots of scripts and re-train users.
5) All of the above often gets you nothing more than "supported OS" status as it will do exactly the same job as the old one (maybe better, maybe more buggy).
So while using old servers for general stuff is barely excusable, there are some VERY GOOD reasons why it won't happen for many. But as other commentards have pointed out, you should be working on the assumption that ALL systems can be p0wnd (old & new, Windows & Linux) and planning how you detect that and restore to a clean state when it happens, not IF it happens.