How can I run the Previews without trashing my current SL client?

I used to love going to the the Previews and would love to comment on them but I have stopped that practice and am wondering if anyone has suggestions on how I may safely return to the current SL after using a Preview.

As I got more serious in my SL( land ownership, money, groups, etc.) I found that when I would return from a Preview run settings, prefs and other details were altered. Is there a way to isolate my test experience from my run every day experience? Sorry I cannot remember some of the details better, been awhile, some were irritating and a few were serious.

I am on a Mac running the latest OS 10.4.7.

I belive a file is located in the SL folder that contains the preferances. (mabey an .inf or mac equivilant) Also by downloading a new client it may not even effect the main viewer.

If you create a sub folder in your applications folder and install the preview clients there it wont effect your main client.

Thanks to the both of you, some clarification...

Tx. I always run a second client because I have the current 'working' Second Life in operation and then have the Preview as well, but they share the same preferences folder/file on my Mac in the user's > myName folder/directory. This is a great convenience when I download a new version SL because it picks up all my settings when I run it but a downside when I am in this situation. Although a hassle, isolating that folder and causing a new one to form for the Preview upon startup I could then switch between them. That is time consuming but possible.

Kingsbury: I run Second Life from a folder inside my applications folder what do you mean by a sub-folder? Inside that folder? Or another sub-folder of its own? And in doing that does that avoid the aforementioned issue above? Does it then create its own User's folder?

I appreciate the help but I had also hoped a Linden dev would have shed some light since they also must face this issue (unless of coarse they have a seperate machine )

I don't know if all the settings that matter are stored in the settings.ini file, but you might try:

Run regular SL and get the settings like you like them, then exit SL.

Create a folder called MainGridSettings, then copy the settings.ini file into that folder.

After you run the preview client, but before you run main grid SL, copy the MainGridSettings\settings.ini file over top of the real settings.ini file.

Note the disclaimer and note I haven't tried this.