Quote - Thank you all for the inputs.    
I'll keep and run my Poser app from my internal SATA drive, and move all the additional runtimes to my external drive.

Also, thank you spacedragon1234 for bringing up the potential problem re:  my system RAM.
I just replaced one of my old 512M RAMs  with a new 1G RAM chip, so it's now 1.5G.  
So far so good, but I'm concerned about the potential problem that might arise in the future.

Has anybody here encountered any problem with a system RAM that's not 1G, 2G, or 4G?

Thanks!

 

I've got 1.5 GB and have had no memory problems. (My motherboard, which is about 5 years old, supports up to three memory chips. One problem I had when replacing my original 512 MB chip was that my two new chips, which had specs identical to the old one, wouldn't play well with it, so I bought a third new chip.

(So if you are going with paired chips, buy them both at the same time.)