OK dude, check this out...

I also have a beige G3 266, and despite having a dual 1.25ghz, all i can think about at night is pimping out my beige beast.

i think that the 800 Mhz G3 card is what you and i both want. -- particularily if you're going to be doing 3D on it, which gets no benefit from Altivec (the thing that makes a g4 so much faster than a g3). So pop that puppy in.

Then get at least 512 MB of RAM in that thing. Apple says that the early beige machines can only take a max of 3x128 chips for a total of 384 MB, but you can get away with 3x256 for 768. There is some spec you need to make sure the chip meets (which i forget, but will get to you shortly) or you can just buy RAM that is certified for all Beige G3's. (A 256MB stick should run about $30)

then decide whether this is a render box, or a machine you want to model and manipulate scenes on. if you want to actually work on scenes, your next big bottleneck is the graphics card. if you're just rendering final images, the calculations are all done on the CPU, so you don't need to blow your dough on the GPU.

most of these beige machines shipped with a piddly 2MB of integrated ATI Rage 128 video acceleration. I would recommend buying the 4MB upgrade chip ($29.99), and then also picking up the ATI 7000 PCI graphics board ($119) This board sucks by today's standards but is the only Mac-compatible board that I have been able to find that has a PCI interface. Since we don't have AGP, we're kind of SOL.

The reason you want to drop 30 beans on the 4MB upgrade is so you can run 2 monitors, which in my opinion allows you to work much faster.

If you still have money after that, consider getting TempoTrio ($179) (USB2, FireWire & ATA133 all on one card) This gives you lots of options for storage, without using up all the precious PCI slots. If it is too much money for you, consider just a regular ATA133 card ($84) Add a fast hard drive to that, and you'll get much faster virtual memory access. Carrara uses alot of virtual memory, so this should improve render times noticeably. Don't bother with a RAID card. I don't think you'll add any real world speed increase with it for the kind of work you'll be doing.

If you are sending files back and forth to another computer, drop in a 10/100 ethernet card ($15-30) into the last remaining PCI slot, so that you aren't restricted by the 10base-t of the built-in ethernet. You'll be very happy you did.

So these are the upgrades that I've been looking at for my G3. It totals about 750, but it is just so tempting to plunk money into that machine... Anyway, I hope that this helps you make your decisions. Please let me know how any of this equipment works out for you if you do choose to upgrade, and I'll do the same for you when I get some of this stuff.

-Scott