Getting xp to work on an xbox not likely but it has been done with windows 2000 and here is one of the many sites that show that this is a true fact and has been done.
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Xbox Specifications
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CPU: Intel Pentium III 733-MHz processor technology with streaming SIMD extensions
Graphics processor: 233-MHz, custom-designed X-Chip, developed by Microsoft and Nvidia
Total memory: 64MB of RAM (unified memory architecture)
Memory bandwidth: 6.4GB/second
Polygon performance: 150M/sec
Sustained polygon performance (full features): 100M/sec
Particle performance: 150M/sec
Simultaneous textures: 4
Pixel fill rate, no textures: 4.8 G/sec (anti-aliased)
Pixel fill rate, one texture: 4.8 G/sec (anti-aliased)
Pixel fill rate, two textures: 4.8 G/sec (anti-aliased)
Compressed textures: Yes (6:1)
Full scene anti-alias: Yes
Storage medium: 2X to 5X DVD, 8GB hard disk
I/O: Four game controller ports, Ethernet (10/100)
Audio channels: 256, AC3 encoded game audio
3D audio support: Yes
Midi/DLS2 support: Yes
Broadband enabled: Yes
Modem enabled: No
DVD movie playback: Yes
Gamepad included: Yes
Maximum resolution: 1920x1080
Maximum resolution (2x32bpp frame buffers + Z): 1920x1080
HDTV support: Yes
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Hard Drive
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The Xbox is the first game console to ever come with a built in hard drive. This is a great feature that they added, which allows many different possible uses. And unlike the PS2, since every Xbox has the hard drive, every game can utilize it somehow. A great feature built in, is where you can save games on the hard drive, which eliminates the need for a memory card. Load times for games can also be reduced by cacheing data on the hard drive, which is faster than loading data off the actual DVD itself. The hard drive is listed on the dashboard as having 50,000+ blocks. The actual amount of blocks available is a little over 300,000. A few sources indicate that there is actually 2 different hard drives being shipped with the Xbox, one being 8 GB, and the other one being 10 GB. Apparently, the Xbox's made in Mexico have the 10 GB hard drive. The extra 2 GB is not actually used on the larger drive, which is kind of a waste.
so i mean the xbox is almost a pc just - the keyboard and mouse.
and can in fact run windows.