hi, i have tried changing screen size by right click on desktop -> configure desktop -> display, it only gave me three standard res. 1024 * 768 being my pressent. Since my screen is widescreen, i need res of 1280 * 800 to work correctly (now the text on websites is kinda blurry..).. so can someone tell me how do i change from 1024 * 768 to 1280 * 800, when it doesn't show up on display tab?

There are a couple of reasons why it might now show in the menu:

1. FC3 detected your monitor correctly but not your video card.
2. FC3 detected your monitor incorrectly and video card correctly.
3. Both devices incorrectly detected.
4. (I hope it's not this) The dirver FC3 has for your monitor/video card does not support the resolution you desire.

You might try the "Generic CRT/LCD" drivers for the resolution you want. This might mess up your monitor though, as it might have the H/Vsync set incorrectly (Although if you know what your H/Vsyncs should be, you can set them in the same dialogue).

Or you could try updating your kernel, perhaps in an update a newer version if the driver has surfaced (this one is a long shot, I would try the Generics first)

mmm.. i just discovered that you can change display settings by going into System Settings->display, however, i put in as monitor type under the Hardware tab, LCD Panel 1280*800. However, as i do that, i still cannot change the display setting to 1280*800 :|.. anyone know what's happening?

after i clicked ok, it says:
Display setting changed
You need to log out and restart the X server for the changes to take effect.
Configuration was written to /etc/X11/xorg.conf, original configuration saved as /etc/X11/xorg.conf.backup.

i logged out and logged back in, it still didn't work.. i'm using KDE if that helps :|

A log out and login, won't restart the X server. Here you have two options:

1. Restart the computer.
2. Hit Ctrl+Alt+Backspace on your keyboard to restart the X server without restarting your computer.

ok. i used both methods, still doesn't work, on the hardware tab it is Generic LCD Display -> LCD panel 1280*800, however, it still doesn't allow me to select that res, still stuck on 1024 * 768 :|.. anyone know how to fix that?

What does it say for your video card?

Also this is a long shot, but what Kernel are you running. As a last resort I would try upgrading my kernel. I think the most current version is 2.6.10-1.766 for Fedora Core 3 (and if you haven't upgraded your kenel your probably running 2.6.9-1.667) . After updating I would restart my computer and boot the updated kernel and see if there is a difference. The only reason I say this might work is that I had a laptop in which the wireless card did not work, but the ethernet card did. I went out upgraded my kernel rebooted the machine with it, and boom wireless card worked like a charm.