For a light to normal workload, you'll want a minimum of 512MB. For any
higher than that, you'll want a minimum of a gig of ram. While there may be
improvements to the amount of RAM used, I can't say if 512MB is really ideal
and don't know how much improvements if hardly any will be made to memory
consumption. Like with XP, 128MB is recommended, but I've found it very
frustrating and sometimes rediculous with this RAM - the eMachines I have
took five minutes to start up with that much RAM with XP. The second I
added a 256MB module, that five minutes reduced to 1 or 2. As a guideline,
I'd recommend going at least double what Microsoft recommends. Since
they're recommending for a typical workload 512MB (256MB as a very bare
minimum and may not always be successful just as XP is with 64MB), go with
1GB. My computer's got 768MB of RAM, but I'll be adding a gig module this
summer, bringing me up to 1.75GB of RAM - that should definitely avoid
having HD accessing problems and plenty of room to spare. I've got a 250MHz
Cyrix Compaq running XP. (Believe it or not, not any slower than Windows 98
even with the Luna.) It's got 128MB of RAM (originally 64MB) and with very
few things running and installed, I still only have about 35MB of free RAM
when in idle.
Windows Vista (my guidelines)
256MB RAM - very bare minimum; not guaranteed to work on all systems and
definitely some features are/should be disabled
512MB RAM - decent for a light to mid workload
768MB RAM - decent for a mid workload
1GB - optimal for a mid workload to fairly high workload
1.5GB - optimal for fairly high workloads
2GB - optimal for any workload unless you're crazy
Windows XP (my guidelines)
64MB RAM - very bare minimum; some features should be/are disabled
128MB RAM - decent for a light workload
192MB RAM - decent for a light to medium workload
256MB RAM - optimal for a medium workload
512MB RAM - optimal for a medium to high workload
768MB RAM - optimal for most of any workloads
1GB RAM - optimal for any workload unless you're crazy