WhAt would u use
Sliverstone, Seasonic, Corsair, Antec, Coolermaster, PC Power and Cooling and a few other brands that are reputeable. This is in no particular order because the deals and specs at the time would influence my decision.
I look for a few things in a new psu, a single 12v rail, at least 80+ bronze rating, enough pci-e 6/6+2 pin connectors to facilitate all the GPUs I ever plan on using.
I would also consider moving towards replacing that GPU if you ever want to upgrade it instead of putting it in sli with another 440. Selling your current GPU and moving to something like the 6850/70 when and if the time cones that you feel you want an upgrade.
Before upgrading RAM run a log of your usage and then use your computer as normal you may be surprised how little you use. You may not need to go to 8gb. DDR2 RAM is unfortunately overpriced compared to DDR3 but not as poorly priced as brand new sticks of DDR1.
Also don't worry about changing your PSU and grata on your oc