The new RAM (1gig's worth) installed like a charm, just popped it it, re-started, and the "General" tab on "System Properties" showed a nice shiny new "1.5 GB" for the installed memory.
I am already seeing the speed improvement on my system, with stuff that sometimes took a second or two to show up now coming right on the click/hover. That is, needless to say, the good news.
The bad news is (you guessed it) that SecondLife doesn't load any farther than it did before I tripled the RAM. There seems to be a bit more detail in the partially-rendered scene, but it is not closer to my being "in" than it was when I was at 512mb and the "integrated" graphics.
So now I have to ask myself, "do I shovel more money at this?" ... I have conflicting adages swirling around in my brain ... "in for a pence, in for a pound" vs. "good money after bad", etc.
Needless to say, it really pisses me off that this has worked out this way ... PLUS there was supposed to be some cool video editing software bundled with the Radeon7000 board, and I've not been able to get TigerDirect to make good on that ... despite there being no sign of this software in the box, in with the board, on the install CD, or available via a download site! Talk about adding insult to injury!