Well, I can only suggest your saving up patiently as I did for a stronger machine and quad-core is the best way to go, as far as I'm concerned. And trust me, you will NOT be disappointed with the results!
Rendering fractals is not like rendering traditional 3d I guess... My render times can take up to 10hrs for a single frame and I have a I7 hexa-core @ 2.8Ghz... And yes, powerful PCs are a good investment
Well, I still have my Pentium 4 computer and will try Mandelbulb 3D on it, just to see what happens--if anything at all, that is! I almost bought a dual-core machine but decided to spend a bit more and got the quad-core which seems to have been the best bet. But I waited patiently for a long time, saving up money for the Quad. And I'm only having a chance now after many weeks to really get rolling with some of the more demanding 3D graphics programs which are out there. But the whole thing is just great and I certainly recommend your getting a stronger PC for...2011!?