Dell Dimension 8200 RDRAM upgrade question

I have a Dell Dimension 8200, Pentium4, 1.9 GHz. It has 2-128 MB PC800 RDRAM modules. I do not know the FSB MHz or if it is 40 or 45 ns. I wanted to add more RAM to the two empty slots.
Dell Tech Support tells me I can only fill the two empty slots with 128 MB modules. If I go with larger modules (2-512 MB), I must remove the 128 MB. Is this true? What do you recommend I do to upgrade the RAM?
Two-512 MB of RDRAM will cost >$500, is this upgrade worth the money?
Should I look into a new computer? This one is four years old?
Thanks for any thoughts on this.

the cost of upgrading RDram is not proportional to the benefit. one of my other machines is running 512 MB of rdram and I am in the process of building a new machine. after looking at it I decided I could replace the mobo ADD 2 GB of PC3200 for considerably less than it would cost me to get 512mb more of RDram.

I don't know if this will help you but one of my PCs is a Dell 8250 with RDRAM. I used CPU-Z and found the manufacturer of my RAM to be Samsung and also the part number. I was able to match the exact part number from an online vendor (ZipZoomFly in this case) and buy additional Samsung RDRAM. In my case I had 512MB (2x256) and added another 512MB (2x256). Buying the brand name RAM from ZZF was actually a little less expensive than the generic online sellers of PC memory.

My memory was non-ecc (according to CPU-Z) but Dell only offered the much more expensive ecc memory on top of their already high price. That's one reason I went with another vendor.

Buying more of the same made the job easy but in your case you are getting different sized RDRAM so our situations are not identical. It is my understanding that you can mix RDRAM sizes as long as you keep the right pairs together. The larger sized RAM should occupy the first two slots though. However, I suppose it's possible that Dell has configured their systems to not support this mixing. I don't know. You can try it and see.

BTW, I understand iss' point but I went ahead anyway.