Improving my PC

Hi guys.

Im planin on improving my PC, and I stumbled on some stuff that I cant understand:

1. Im considering to buy a ATI Radeon HD4850/70, and I saw in its pictures that it has 2 differant DVI exits, so my question is, do I need to input 2 differant DVI cable, in every exit for the video card to work?

2. I also want to increase my RAM from my current 1gig to 2, will it be enough for the video card to work properly?

Thx in advance.

I have Intel Dual Core 1.86gigs.vl69

How about PSU? We need to make sure it has the right connectors/Wat/Amps , Etc..