Installing the drivers that came with your new nVidia 7800GS card will certainly be old drivrs.......that card came out over 3 years ago. Don't let the date the card came out influence how good the card is.......it's got quite a reputation as being one of the best (despite it's "age"

. But in the 3 years since there has been numerous features added or enhanced with driver updates.......SL may or may not work with those old drivers. It's worth a try but don't be disappointed if the drivers are not up to par.
Here's a link to the most recent driver for that card:
http://www.nvidia.com/object/winxp_182.08_whql.htmlAnd here a link to the listing for archived (older) drivers for that card:
http://www.nvidia.com/Download/Find.aspx?lang=en-usBoth links are useful. Most of the time the most recent driver is the one to have......but sometimes, due to individual computer setups, the program you are using that requires specific features, the most recent just does not work well. You need to find the most recent "older" driver that will work for you and your computer setup. Hence my listing of the two links for you.
Replacing drivers is not hard, though, if not done correctly you could create more problems than you had in the first place. The nVidia recommended way to update your driver is to first uninstall your older driver (if you have more than one driver listed, then uninstall all of them). Your computer monitor will work.....just at some poor quality until you get the proper driver installed.
My method:
Go to nVidia's driver download site and find the driver you want and download it to your hard drive (save it......don't do any auto install from any site).
Uninstall your current driver. You will be required to restart for the uninstallation to be completed and when your computer boots again Windows will "find new hardware" and want you to allow Windows to search for a driver.......don't let it do it. Just close the box.
Install the driver from the downloaded file you saved.
Again you will be required to restart for the installation to be completed.
You're done.....but you may want to configure your settings. Do that with the nVidia Control panel.
Now if you find the most recent driver does not work for you then you will have to find one that does. That's why I gave the link to the archived drivers. Download a few of the older drivers in reverse order and save them to your hard driver like you did before. Then one at a time uninstall the current driver and install another until you find the first one that works for you. A little tedious but it's about the only way I know of to get the proper driver for your system.
I use nVidia 8600GT with driver version 178.13 with success in SL. It might work for you too. It's listed in the archive for your card.
Only comment I have on the ATI 9200 card is that I had the 9250 when I first started SL. It worked but over about 6 months time, with all the SL updates and upgrades the card was getting rather flakey........struggling greatly to keep up. That was about 3 years ago. I would say that card would perform quite poorly with today's SL (if it worked at all).