First, it appears the discounts are only on the "upgrade" versions. Second, you are talking upgrade prices against retail prices. The discount appears to be only on the upgrades to W7. If you buy Vista Home Retail (which seems to be the requirement for the free upgrade) is around $224 at NewEgg. The $90 price for Vista would be OEM, the upgrade needs to be "Retail" versions. There is another deal for OEMs, but I think that is just specific manufactures.
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