Well technically, you can run as many as you can fit. I believe if you search around you can find os 7 legally, but for the later versions, you can get them cheap off ebay.
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Edit: I just realized I have 7.5.3 on my drive which I obtained legally online after much searching a while ago, if you want I can send it to you.
Well technically, you can run as many as you can fit. I believe if you search around you can find os 7 legally, but for the later versions, you can get them cheap off ebay.