Go for at least a 7000 Series Nvidia Card if not a 8000 Series.

I use 8600GT's (note NOT GTS or GTX, the elcheapo card is more than enough) and it rocks along.

I did 2GB of RAM also because its dirt cheap and in the long run you save maybe $100 by only having 1GB in each and I'm talking AUD not US as well.

As far as parties go, your team is nice, but be careful, your team is nice at seventy, it might be fairly subpar espeically till about 40.. so dont be upset if its slow. Prot Pally doesn't really start to get even playable till 20, and really its only good 35+.

I personally went with Warlocks who dont have as much up front instant cast dmg, but they have three forms of CC, Seduce, Fear and Banish/Enslave. Most people dont like Seduction, they feel its much flakier than sheep. Personally once you have a good seduce macro it kicks the crap out of Sheep due to the fact your warlock can be stunned/feared or whatever and your Succubi can be on 'stay' well out of the way keeping 3/4 targets seduced.

Your going to probably want two sets of macros if you want to do both - one for PvP and one for PvE - CC works best using Focus Macros and you willl use up all your Focus Targets in PvP by using them as your 'main'. In PvE you would probably use Party1 in all your macros and make this your paladin.

For PvE you might want to try something like Pitbull for your UI frames, personally I found it buggy as hell and annoying to setup. But being able to see all your pets targets and your party members targets is awesome, lets you verify who has what target for pulls and such.

The best advice I can offer you is dont be in a massive rush or your project will suddenly become duanting and massive. Take each step at a time and design everything and think it out beforehand.

1. Setup your machines
2. Setup your WoW Folders on each machine, make it easy to start your clients, login to your clients. Have you interface folders shared and writable so you can update them easy.
3. Think hard about your interface/macros, if possible try use all Ace2 mods so you can use the WoW Ace Updater for updating easy.
4. Setup all your buttons and get started, and dont get too daunted by how slow it is 1-20, after that it gets much quicker.

Take photos of your setup and putting it all together and put it up in the SS forums when your done. And Welcome!