The default configuration of your computer is a Pentium 4 2.8C, 512MB DDR (two 256MB sticks) with two open slots, and a Geforce FX5200.
The short answer is yes, your computer supports Windows 7. However it won't run very fast on only 512MB of RAM, as that's the absolute minimum required to install Windows 7. I would recommend an upgrade to 1GB or more if you don't already have it. 2GB would be the best.
Also, the Geforce FX series of videocards do not support the transparency effects of Windows 7's user interface (Aero). Geforce 6000-series are the first cards to support this. The operating system will still work, it just won't look very good.