<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Is 700:1 "that much" superior?</font>
No. Take those ratings with a grain of salt. 500:1 and 700:1 both denote current generation panels.
<font face="Verdana, Arial, Helvetica, sans-serif" size="2">I was considering some eBay auctions</font>
Don't! After having 3 TFT failures in the past 5 years, I can vouch for a)the need for a good warranty; b) for the high cost of repair outside of warranty.
<font face="Verdana, Arial, Helvetica, sans-serif" size="2">I am down to an in-store special at FRYS ELECTRONICS (which is a 500:1 ratio 19" monitor by GEM) or COSTCO (which is a 700:1 ratio 19" monitor by Sceptre). Both have the same standard resolution and built-in speakers.</font>
After perusing their respective websites, it appears that GEM offers a 3 year warranty (2 years only on parts) vs. 1 year for Sceptre, and that every 19" GEM looks a ton better than that bulky Sceptre! No contest. Forget about the speakers, any built-in speakers will sound worse than even a $5 dollar standalone pair.
17" and 19" desktop LCDs have the same 1280x1024 resolution. The 19" will display a bigger image, not a more detailed one. Recommended if the viewer's eyes are not young any more.
<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Is it likely or unlikely that this card with work with two new LCD monitors?</font>
The monitors you are considering have analog VGA inputs, just like your current CRT's. They
will work with the current graphics card.
If you could find digital LCD's with DVI inputs at a premium you can afford, I would definitely recommend those for their superior clarity. However, graphics cards with dual DVI outputs are a rarity, with the cheaper ones running slightly over $100.