help upgrading memory in a G4 desktop

Hello,
I bought a G4 desktop from a friend a few years back. I'm editing Raw files on Lightroom these days (from a 8.5MP camera/soon to be a 12.5MP camera - 22MB-30MB files) and it's really slow.
I know the computer is pretty old; but I thought I'd look into maxing out the systems capability memory wise.
Since it's old though, I don't know what it can be upgraded to.
Here's the details from "about this mac"
Nameower Mac G4
Model: Power Mac 3,5
CPU Power PC G4 (2.1)
Speed 867MHZ
L2 Cache 256 KB
L3 Cache 2 MB
Memory 1.5 GB
Bus Speed 133 MHZ
Boot ROM Version 4.2.5 f1

Is there any room for upgrade on this computer - internally?
Thanks for the help.
M

Only thing i see would be to upgrade your Processor (currently 867mhz). here's a list of upgrades that would work with your computer. range from $175 to almost $500, but its still cheaper than buying a new machine. im currently thinking about doing the same thing. it looks like your RAM is maxed out tho. good luck.

As jackson advised your memory is at the maximum as Quicksilvers have three memory slots and 512MB PC133 is all you can fit in. Had used a Mercury Extreme 1.3GHz upgrade from OWC at www.macsales.com for years and found it fast and reliable, but now if you are going to invest in an upgrade, 1.6/2.0GHz would be the go.

Bear in mind MDD FW800 machines are coming down in price. A 1.42GHz dual processor would suit you just fine and that model will take four modules memory to give you 2GB.