SiS Mirage 3 671/771 - Can't make it work on Arch64...

Question

Hi folks! I'm new to the forum (first topic! yay! ) and also new to Arch Linux. I am a former Slack user, although I was using Kubuntu 9.10 till yesterday (shiped with my new notebook...).
The thing is: I formated this notebook. Made a Dual Boot (Win + Arch). Installation worked just fine, i have a fully functional Arch environment. But the problem is about Xorg. The Videoboard is a SiS Mirage 3 671/771, so I installed xf86-driver-sis and xf86-driver-sisusb with Shaman (Chakra + tools are installed as well). But if I update my xorg.conf to use any of them, the X11 won't start, returning "No screens found" error. Using VESA, weird stuff happens... Strange artifacts on screen, "choppy" moving/resizing windows...
Before formating the machine I checked Kubuntu's drivers and xorg.conf (made a copy of the last one), and Kubuntu was using "sis671" driver, and everything was working perfectly, including some (I repeat: SOME) of the Desktop Effects. Searching through the forum, I found two posts about this issue but nothing described there worked for me. Links for those posts:
Sis graphics driver on linux?
[Solved] Sis mirage3/sis 671
This last one says [Solved], but i couldn't find clear instructions on how the author did it. Apparently, installing this url's drivers worked for a lot of people, but I can't manage to install/compile/use them.
I'm using Arch64, for my computer is a Pentium DualCore T4300, 4Gb RAM, and ArchWiki says Arch32 doesn't support more than 3Gb RAM. Can this be the problem for me? Maybe the only people who actually installed the drivers from that URL are those using Arch32...
I don't have to say everything works fine in Window$... crappy-SiS refuses to release a decent 3D driver for SiS Mirage on Linux, but work just fine with M$ OS. This annoys me...
Afterall, is there anyone who can help me compiling/installing/making-work this crappy video-board? If I could make it work just like the default Kubuntu installation, it would be great!
Sorry for the long (double)post and my awful english (I'm Brazilian),
And thanks to all in advance.

Answer 1

@mikkle, thank you so much! I followed the instructions to downgrade the xorg-server, installed the 64 bit driver and now it works perfectly! I have my resolution of 1280x800px and some of the desktop effects on KDE 4.3 (Chakra Project).
Anyway, if anybody else goes through the same and would like to know how to proceed, I will describe the steps here. First, I upgraded the system:
$ pacman -Syy
$ pacman -Syu
Then, after everything was done, I followed the instructions at the Arch Wiki: Downgrading Packages to downgrade xorg-server. Also did the trick to stop pacman from updating xorg-server.
After the downgrade, I installed SiS drivers from this website (I used the one precompiled for Ubuntu 64 bits).
Then I proceeded to reinstall Chakra project (uninstall it an install like described at Chakra`s website). About xorg.conf file, it is exactly as the one above, with the obvious difference to use "sis671" instead of "vesa" at the Driver field, looking like this:
Section "Device"
Identifier "Card0"
Driver "sis671"
All of those steps took me about a day or so to perform, but I would type one command and go out for a coffee, a smoke, some chating...... and come back after two, maybe three hours. I believe that with some more dedication (and a better internet connection) it can't take more than 8 hours.
One last recommendation: if anyone will perform the same steps, make sure to read everything, downloading everything you believe will use, and really understanding the procedure before doing it! Seriously, I mean it! Understanding the procedure is the most important item here! Other than that, it is pointless to mess so much with your system, and in that case I would strongly recommend the use of Ubuntu (or anything alike...). Of course I had some other complications, it wasn't as simple as it sounds, but my knowledge of Linux was essential on solving it, knowledge that I acquired in years using Slackware (that has the same philosophy as Arch), reading tons of tutorials like those and really understanding all of them... The only reason I changed to Arch is Pacman (makes my life go faster)!
Thanks again to everyone that helped! Can anyone add a [SOLVED] to the thread's title?!