will Mac OS X Snow Leopard INSTALL on a IMAc g3 slot lOADER?

No. You have a PowerPC system, and Snow Leopard is x86 (Intel, though possibly AMD in the future) only.

Depends on exactly which model you have, but I think you can use 10.4 (Tiger)

See here http://support.apple.com/kb/HT2176 for 10.3 (Panther) requirements.
See here http://support.apple.com/kb/HT1514 for 10.4 (Tiger) requirements.

What speed CPU? Do you have firewire ports?

If the answers are "350MHz or lower" or "no firewire ports" then you can use 10.3. If you're faster than 350MHz and have firewire, then you can use 10.4.

Doing "About this Mac..." from the Apple menu will tell you the processor speed and how much RAM is installed. Both are important info for getting fast help around here.

That's what we needed.

Officially your iMac--known as a "tray-loader" for its optical drive type--can go to Panther (10.3.X). Panther is quite better than Jaguar (10.2.8) that you now have. You probably need more RAM than 160MB for even Jaguar. I feel that 384MB is about min for that OS.

The big problem is that the early iMacs came with painfully small hard drives --4 to 6 G--and OSX need a lot of free space on the disk for efficient performance. It's hard to keep a Jaguar system under 2G with a few useful apps installed.

Bottom line: you'll spent money for a hard-to-find retail OS install disk, more RAM, and a bigger hard drive, and you'll still have a slow computer that will always struggle with modern web pages. If you want to upgrade and experiment as a hobby or learnign experience and you can afford the parts and time, by all means--go for it. However, if cost is an issue, throwing money at this unit is not cost-effective in terms of how much more yo ucan get from it.

Well, he's 1/3 of the way there, having already upgraded his hard drive to a 40GB one. If he can get a good deal on a Panther Retail boxed installer CD set (like this one), then he only needs to add more memory. Having invested way too much $$ on older Macs that were past their prime, I agree with you. Spending a lot of money on a 333 MHz iMac in mid-2010 is not a good use of funds, that could be saved and put toward a faster/newer Mac.

Chill. And read more carefully. People are suggesting that it's probably not worth spending money on the iMac to get it up to spec, nothing else.

" first off I HAVE NOT SPENT MONEY ON MY IMAC and second of all I DONT LIVE IN AMERICA"

I was referring to myself when I commented, "Having invested way too much $$ on older Macs that were past their prime." I obviously don't know how much money (if any) you spend on your Macs or where you live. You indicated that your iMac has a 333 MHz processor. If you check the specs here for the 333 MHz models, the "Standard Optical" drive info lists a 24X tray-loading CD-ROM drive. If your iMac has been modified from its original factory configuration, there could be hardware differences. If you say that you have a "slot-loading" 333 MHz iMac, I'm not going to contradict you.

Fine. I am sorry for your frustration but I think I will leave this thread to others more tolerant of being yelled at for trying to help.

Hi Youngzink,
having Apple Stores here (I live in Canada, by the way) wouldn't help you much in your case, since there is almost nothing available for that ancient Mac.
And by the way, writing in CAPITALS means SCREAMING in .net language - IF you didn't know...