In doubt about computer sale price?

I have a computer that I recently bought (last month). However, I'm planning to sell it but I'm uncertain of how much I can sell it for; the specifications are:

- AMD Athlon X2 64, 2.3 GHz
- 3GB DDR2 667 Kingston
- 80GB 7200 RPM SATA HDD
- NVIDIA 8500GT
- 512MB VRAM
- Sound Blaster X-Fi Xtreme Audio
- DVD-RW/R DL
- Windows XP Professional/ Vista Business
- 19" Brand new IBM ThinkVision monitor

It is a Lenovo A61, I checked at ebay, the ones with basic specifications (very basic in comparison to mine) are selling at about $529.99
If you had such a computer, how much would you sell it for? (It's in pristine condition)

$200 for the computer
$100 for the monitor