Till now I still on Windows XP 32 with a lot of happiness. I still kicking on Sketchup for daily use and OSS for the rest, though I will get Win7 anyway once I buy a new netbook. What I missed then if I stayed on this venerable OS?
Win7: Easier to use and more organized. This seems the main mantra in Se7en, every user will agree including me. But don't misunderstand the meaning, it didn't mean to be faster.
Years of XP usage did give me a lot of understanding in XP's internal that remain the same as in 7. Some are:
We are still dealing with registry
There is Run command box (though hidden)
There is cmd box too
Same directory structure (there is some junction that handle compatibility if you don't know already)
And all core component settings are still accessible through msc files
Shortcut of Win+? still works the same too
Hence, Windows 7 did not forgot to maintain compatibility, What 7 does is hide the access to the more (in-depth) usage (I'm talk about Run box of course). I have experience where an Win7 user ask me how to do stuff, for example he ask about how to use the bundled partiton manager in 7. Thats a new thing for me but I could guess where it be.. I ask him to Win+R and type diskmgmt.msc and go. There is!
Sound trivial but that's the point when you know the internals, these stuff remain the same with NT5 (2000 and XP) and probably NT4 (I don't know). Yet I still able troubleshooting Win7 user without seeing it/ using RD.
It's not faster when you just re-learn where to find stuff A or B and so on in Win7 which being re-organized. Unless it made more accessible thru a new shortcut or probably a mouse gesture. And I don't say I'm a slow learner but when I given up on finding new thing, I fire up Run box to completely ignore the new interface. And I still reach the goal did I? Why the Run box is hidden then? Hmm, maybe I'm not a fan of fancy UI..
In fact it took me 3 years before I could love XP theme (Royale Noir), before that I using Win2000 style exclusively.
Virus and security?
Obviously we don't know the future of Win 7 in this case. Even after Gates told their engineer to write secure code after XP. Who knows? Major hackers and Virus makers are still targeting on Windows anyway. The hole is in the process to be found. IMO "virus is actively happy in mainstream OS" that is when an OS is abandoned, they also abandoned it as a target. Who knows... Some virus indeed only needed to be dealt by a smart user who recognize the difference between virus and not, the rest is handled by smart browser. Again that sounds trivial but maybe it is.
Fundamentally, What I think from an OS is how it sufficiently deals with software usage (productivity) and manage hardware resources. And I always pick my software carefully, like prevent any automatic updater. With OSS I'm quite happy too, they are mostly low at resource usage thus bring me more multitasking that my 2Gigs RAM could give.
My XP itself is no ordinary anymore. I have turn it into a DVD of unattended Windows installation with my own services tweaking, interface, settings, directory structure and preselected of productivity software all in one way process. BTW isn't the best OS is the one that tailored for your needs? Like Gentoo way... so what do I expect more on 7?