So this isn't what Ehtyar needs, but for anyone who may come across this thread looking for actual computer forensics apps, another one to add to your list is WinHex: http://www.x-ways.net/winhex/
. Quite pricey, but has an awesome featureset. (Though I don't know the ones you listed, so I can't compare).
Ehtyar - it seems you have what you need, though you didn't mention a good AV program. Avira (http://free-av.com/
) is pretty good and free. Your users will need that, and a firewall as well, if they don't have one yet. I'm using ESET Smart Security, which is a firewall and an AV (a repackaged nod32), but for AV alone I think Avira was better (certainly its scanner is faster).
For other tasks, I don't think you can do much better than Process Explorer. WinHex and the other forensics apps will do all PE does and more, but they are complex and really expensive, and probably won't do much for weeding out spyware and such. WinHex is intended for post-mortem analysis; I'm not sure it will monitor processes/files in real time (it may though, I wouldn't be surprised).
For real-time spyware (and suspicious-ware) monitoring I thougt ThreatFire was pretty neat (www.threatfire.com
). It used to be free, but now costs 30 Euro for 3 machines. I used to run it on my laptop, but it never detected anything so I decided I didn't need it and can't really comment on its efficacy
(correction: Threatfire is still free for personal use, but you need to check the feature matrix to see that. The 30 Euro license is for commercial use and apparently easier updates)