I use a VGA compatible controller: Silicon Integrated Systems [SiS] 771/671 PCIE VGA Display Adapter, and i can't get a screen resolution higher than 800 x 600. i really need some help.

You could download this http://dl.dropbox.com/u/983756/sis671_10.x.tar.gz then uncompress and copy :
- xorg.conf in /etc/X11/
- and sis671_drv.la and sis671_drv.so in /usr/lib/xorg/modules/drivers/
Yous hsould have a nice 1280*800 screen
After that you can also download another maybe improved for lucid driver from http://ajoliveira.com/ajoliveira/gen/bin/sis_driver_32-bit_10.04.tar.gz
uncompress it and copy the .so and .la files as above said, also read the .txt file but it should already be done with the first download.
It seems you will NEVER find any 3D driver for a sis671.
Hope it helps.

Thanks. When i tried to copy and paste the xorg.conf, it said i dont have the privileges to do that.

You may copy files in /etc or /usr directories only as "administrator".
If you are used to "nautilus" file manager you can start it in a terminal by typing "sudo nautilus", you will be requested to type in your password and then will have a nautilus with FULL administror rights, I mean which allows you to do anything to your computer, good as well as destructive, take care and think twice before doing something.
In this nautilus window you can work with two panels and drag one file from one panel to the other (click F3 to switch to and from 2 panels).
You can for exemple have in your left panel the file you have downloaded, you uncompress it there and open the directory which is created, in which you find the files which must be copied.
In the right panel you open /etc/X11/ and drag in it from the left panel the xorg.conf file.
You do the same with the two .so and .la driver files, dragging them to /usr/lib/xorg/modules/drivers/
Here I am working a Lucid Lynx system with 2.6.32.22 kernel, don't know if these new drivers will work with an older kernel.

still gives error, but a friend showed me how to use the cp command on the terminal, i completed the above processes, but my gdm refused to start, i had to reset the xorg.conf file, using the reconfigure command, and i'm still stucked. let me see if i can upload my own xorg.conf file and the log file. But can i upgrade my kernel to a higher one maybe then your process might just work.

Sorry I cannot do more, as I said I am working a newer kernel as I upgraded my systel to Ubuntu 10.04 Lucid Lynx and I am very satisfied with it.

Thanks, i'm very grateful. But am currently using Ubuntu 9.04, and i have a live cd for 9.10, can i upgrade with the cd and will i lose any of my installed programs?