If you are just using the computer for word processing and the net (which is what most old computers still in use are used for) how much computer do you really need? I used a 2.4 gh pentium 4 for years running xp and really saw no reason to upgrade. It did what I wanted it to at what I felt was an acceptable level. Finally, my MB died and I was forced to put together another system, which ended up being a dual core I got from an auction. Going from a single core at 2.4gh with 2 gb ram to a core 2 duo at 2.33 with 4 gb ram I see very little difference in performance.
Rather than throw away an old system on XP, I'd bet all the xp systems will run windows 7.
Windows 7 system requirements - Microsoft Windows
If you want to run Windows 7 on your PC, here's what it takes:
1 gigahertz (GHz) or faster 32-bit (x86) or 64-bit (x64) processor
1 gigabyte (GB) RAM (32-bit) or 2 GB RAM (64-bit)
16 GB available hard disk space (32-bit) or 20 GB (64-bit)
DirectX 9 graphics device with WDDM 1.0 or higher driver
While at first blush it may seem that you won't be able to install a new video card ect... which is true, most of these systems wouldn't support the hardware even if they did still support xp (ie. Older systems use PCI or AGP video not PCI express). Also most people have no idea of what the updates really even do and are oblivious to what it even means that microsoft is no longer supporting XP.
Additionally, most of the drivers are made by a 3rd party, and they certainly will have an XP driver as long as they feel these users are buying their products.
I think we are going to find that Microsoft's lack of support is not going to create a "wave" of upgrades and a surplus of XP machines.
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