Most cost-effective double monitor system?

Propose new build with two monitors using 2-3HDD on RAID1 based around the AMD 955 chip.
My existing Samsung Syncmaster 193v (discontinued) has a D-sub connection and there's nothing wrong with the screen so I'm loathe to part with it for no reason. On this basis for the main monitor I'm looking at a DVi-1 connected item up to 20" - preferably non-widescreen ('cause I like the extra depth that '16-9' doesn't provide).

I'm also undecided which AM3 mobo to get. (I've already ruled out the MSI 790FX GD79 'cause it don't leave enough room over the RAM for my intended Mugen 2 cooler) So.....

Can I go the HD4870 route and power both off the one card using a VGA adaptor for the older screen?
Or get two HD4850 cards and work the screens independently?
Or get a mobo with integrated HD3300 graphics?

We meet again! I confess I was more inclined to go for the Asus M4A79T mobo on that occasion. But have since learned that both boards were designed exclusively for the AM3/DDR3 platform, share the same TDP and, at least here in the UK the Blackstar is £30 cheaper delivered. But there is just one UK Blackstar supplier it seems. I know, I only need one board! Still my heart wants to go for the ASUS together with a Sapphire HD4870 card.

But following your latest post it's finally sunk in that I can add add a series 4800 graphics card - the Sapphire HD4870 1GB (£155 delvd) or perhaps the SAPPHIRE HD 4850 1GB (£132 delvd) and get a dual screen system using my old monitor as the second screen.

Eureka! I hear you say.

So,
Blackstar, 955 cpu and Sapphire HD4870 1GB or
Blackstar, 955 cpu and Sapphire HD4850 1GB
or would you suggest an alternative Sapphire card!!!