I changed my PC some months ago and also I built a barebone (little case) Pc to use it as a dvd/dvx player and sat receiver some times ago.
First I tried an AMD 3000 like the one you are planning to use, I've to say that I still don't understand how are named the last class of AMD processor, because "3000" doesn't stand for "3ghz" and it is about 2.4 ghz even if reading the forum dedicated to this kind of things it seems that it's faster. In any case I got confused, and the system had some problems with windows xp (frequent shutoffs without notice, but maybe it could be some trimming faults from me), and because I wanted a true 3.0 ghz cpu I decided to go to the safest solution, even because I were not very deep in knowing the last features of the cpu/motherboards and so on and bought a Pentium 3 3.0 ghz and Asus motherboard that is what I'm using just now. The combination motherboard/cpu with Intel is more simple and easier for newbie (like me...) because they are more software controlled by the bios and I had not to change a lot of jumpers. The processors you are planning to buy should have the same performance, what I can suggest to you is to spend more money on a very good VGA card, like an ATI Radeon 9800 (I have it) or one of the last NVIDIA card, with a minimum of 256 mb of memory. I understood that while using graphic programs (or games
) the video card is the most important thing. The rest of the equipment is not mandatory as far as I know so buy the cheapest thing you find, buy a good 400mhz module, I've 1 gb of Ram but with 512 mb you're ok and keep in mind that the last cpus and video card processors produces a lot of heat. If you don't plan to overclock some components the normal fans are ok but I suggest you to keep the case of the pc opened or if you cannot buy some good aftermarket fan (they are not too expensive) and add some of them to the case.
Talking about video cards I experienced the different load of heath on the cpu with a poor card and with a good card. During a render with the old card the cpu heat raised a lot, sometimes the PC shutted down for protection against heat. With the new one The cpu stays almost cool while the video card processor raises the heat but it seems less critical.
If you plan to build the PC from scratch you'll save some money and search the best thing that you need, the already made PC usually have only some components that are very good, for example they sell them with a monster cpu but only with the standard onboard video card... I don't know if in Argentina there is ebay, in any case you can consider buying an used case (I bought mine on ebay) eventually changing the power supply which is the critical component of them (they are not too much expensive). I suggest you not to buy an used hd and to point a fan on the hd itself into the case because the last hard disk types spread a lot of heat too and I think that sooner or later it would be a cause for some tragic failure and loss of a lot of
Poser work... I've a fan pointed on hit and it's almost cool all the time. I prefer a desktop case instead of a middle tower because I can put my hands into it more easily...
If you have to put the CPU into the motherboard yourself remember to use a good conductive-paste between the processor and the fan. Putting the cpu into the motherboard it's very easy and you can't do the wrong thing if you're not very, very
noob...
I hope that I helped you (or maybe added some more confusion
... lol )