Desktop goes bad.

Seems my desktop is about to die soon and I am looking to get a PC with somewhat the same features maybe updated and start working. fortunately I have another 2 desktops around but the issue comes because they are lower poweered and sometimes even less performance wise.Maybe getting a new desktop is an option or just go all the way and replace the laptop with a much better one.So I am thinking one with the bellz and whistle, so maybe a better faster computer with a good 3D graphic card and also a good RAM memory.  Of course I want a whole Linux workstation, everything has to be compatible and everything should work out of the box, no weird drivers or proprietary component. Linuxquestons usually offer good advice on this, thats how I just order a small webcam with high quality content.So here is my hardware guess:

Hard disk
I would want about half a terrabyte at least for the storage althought I will still rely on my external HD
Video Card
I want a 3D card, like an Intel or a NVIDIA one but not the highest end I really just want to have 3d acceleration.
Audio Card
I really want something more professional although I am relying on external cards for this one.
Around 4G of fast RAM, really accelerated
Dual core or quad core althought I dont think is necesary a 64 so I will keep on the x86.

If you had a special comment or suggestion please hit me up.