Hi Erik,
We use zeros here but we also looked at recycling existing older workstations using the MS Thin PC build (essentially Windows 7 embedded). A couple of things we found:
Licensing: Unless you have a Windows license with SA on your existing workstations you'll need a VDA license to use those workstations with View. Good news is, you get a "free" Thin PC license with every VDA license. Note that you need VDA licenses with zero clients too.
Performance: Didn't see any real downside with older workstations until we tried running multiple full HD monitors and RTAV - and then we saw some slowdowns on older hardware, so be sure you understand your use cases. (Minus points for zero clients here - so far, no RTAV support at all.)
Maintenance: Still need to patch those Thin PCs, so for us this was a major negative. The beauty of zeros is zero (well, almost zero) maintenance, and the Teradici console makes configuration/firmware updates on the zeros pretty simple. Gets you out of the monthly patching drudgery at the endpoints but you still need to patch your master images and refresh.
Compliance: The biggest draw for us with zero clients was compliance (we're in financial services) and not having any local storage was huge plus at audit time. With Thin PCs your users shouldn't be storing anything locally either, but the hard drives are still there and still subject to audit.
Hope this helps.
Geoff
