My low-end video card will not display above 800x600 in Linux

[HGeneAnthony]

I recently got a cheap PC I'm using strictly for my personal server. I have Windows XP Pro and Debian running on it. It's only a 500MHz machine with around 128MB of RAM. XP Pro runs fast (after you knock off some services, eye candy, etc.) and will display in 1024x768. However, Debian is hard to use in graphical. I'm using Fluxbox as my Window Manager. I have a 19 inch LCD monitor (my main box and the server run on my KVM). Firefox isn't displaying fully, the text is pretty big, etc. Why will Windows allow me to use 1024x768 but Linux won't? I set up XF86Config-4 with the proper monitor resolutions, what am I missing? If it is running in the lower settings it's practically unusable. How can I improve this? Any help?

[psic]

What graphics card are you using. Do you really need GUI since it's a server? I'd probably buy a cheap Nvidia graphics card (used if you can get it), that should be easy to settup.