Hi, Vlad,
The model PowerMac you have is referred to as PowerMac G3 Blue and White model.
This model can actually take up to 1 GB of RAM.
What speed is the CPU?
In order to run OS X on this Mac, you need to find and run a special Internal ROM firmware update software in OS 9 to update your Mac's ROM firmware.
The update you need is called PM G3 (Blue and White) Firmware Update 1.1
I don't even know if this is still available as a download from Apple's web site any longer
What are your plans for this Mac?
As stock, in this day and age, this Mac is going to be a very poor performer on the Internet with OS 9.
The programs you already have loaded are out of date and there were changes to make OS 9 programs that were modified to run under OS X, but these updates may not be available any longer.
Tthe highest OS X version you can run of this Mac is OS X 10.4 Tiger.
Finding original retail discs for this version of OS X is going to be hard to find and expensive.
The cost of the OS X discs you need to bring this Mac to a more usable machine will Probbaly cost more than this Mac is worth. OS X 10.4 Tiger is over 6 years old and will be hard to obtain.
Plus, to get this Mac to a usable state for today's computing and Internet use may not be worth it either. Some upgrades now are more expensive than your Mac is worth, now, too!
There were CPU ZIF upgrade cards that could bring your Mac to a 1 Ghz G3 CPU speed and Mac video PCI upgrade cards and various PCI USB 2.0 and FireWire cards.
The PCI USB and FireWire cards can still be found here
http://eshop.macsales.com/shop/usb/pci-pcmcia/
Here's a compatible PCI video card upgrade for your G3
http://www.amazon.com/ATI-Radeon-Edition-Video-100-436011/dp/B0002F8MJY/ref=sr_1 _4?ie=UTF8&qid=1357790769&sr=8-4&keywords=ATI+Mac+edition+video+cards
You may need to search eBay for the CPU ZIF upgrade cards as these are not available from the manufacturers any longer. These could be more expensive than your B & W Mac is worth!
If you are planning to use this computer for anything productive, you are going to be better off looking for a Mac that is newer and more modern as these G3 models were discontinued in 2000.
Apple is using Intel technology now and has long since abandoned the Motorola PowerPC CPU/logic board architecture. It is obsolete technology, now.
If you hadn't abandoned this Mac for so long, you might have been able to both ressurect and upgrade this Mac as many upgrades has still been available for this Mac up until perhaps 5 years, ago.
These support forums have been here for a long time and could've been a help to you long, long ago.
Apple is in much better shape, now.
You might consider a much newer used Mac that's a 2007 model or later depending on how much you are willing to spend on a used Mac.
It would make for a better Apple/Mac experience for you by using more recent Apple technology.
Good Luck on whatever direction you decide.
Michel