Just to clarify, do you mean the following OSes when you say "last three operating systems"?:
- Win7 without any service pack
- Vista SP2
- Vista without any service pack
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Oh and in case you're wondering, the hardware requirements are extremely lax - the only real demanding thing is the Vita Fate OP which requires either AVC hardware decoding (should be included in any GPU, integrated or discrete, made in the last 10 years) or a CPU with multi-threaded performance equivalent to at least ~2GHz Athlon 64 x2 or ~1.6GHz Core 2 Duo.
But if you're running without HD OPs, then it should be able to run on anything made in this millennium - the bigger bottleneck would actually be the OS's hardware requirements (I wouldn't really recommend running Win7 with 1GB or less of RAM for example).
Now admittedly I didn't try it on a CPU without either SSE3 (not SSSE3) nor SSE2, but similar to what I alluded to for the OS's own hardware requirements, the kinds of CPUs don't have SSE3 are 15 years old and don't even support DDR2 (which means such systems having more than 1GB of RAM was uncommon).
And remember what I had previously said about Win7DSFilterTweaker in terms of making the OPs work! (I believe this applies to the program "CodecTweakTool" as well).