I have a network with 2 pcs.
What software do I need to make a small render farm for blender ?
if that’s all that you have…
…you might as well just send your files over to that second pc and render
them from there.
If you don’t want to “walk all the way to the second pc” you can
make a small simple script something like this:
blender -b yourblend.blend -F JPEG -f yourfilename.jpg
or check out the help file by typing blender --help from any console.
Hope this helps ya
I didn’t got exactly what you said 
These might be helpful:
http://blenderartists.org/forum/showthread?t=43072
http://forums.cgsociety.org/showpost.php?p=2653655&postcount=500
Check this out: Build Your Own Render Farm
Or you could save up for a few Boxx computers…
If you only have 2 pcs, it is going to be just as easy to copy the .blend and texture files etc onto both computers, open blender on each computer, and set what frames to render.
eg. If you have a 200 frame animation, put all the files required on each computer, set to output to a picture file (eg. png, tiff etc), open the .blend on each computer and set the first computer to render frames 1-100 and the second computer frames 101-200. Then put all the .png’s (or whatever file type you saved as) back on the one computer, open them in virtualdub (some old versions of virtualdub wont load images sequeces, if they dont work, get a newer copy), then set the frame rate and compression (codec) then save as avi or whatever filetype you want.
You could also open the image sequence in the blender sequencer and resave out of there as whatever filetupe you want.
Other than that, you could set up a drqueue renderfarm, but it can be a pain to set up. I have a linux server running the drqueue master, and a slave on the other computers, but it took ages to set up. The only reason I bothered is because there are 4 fast computers plus a laptop in the house, and I need them to join and drop out of a long render (ie like 2000 frames rendering at 30mins per frame).
Personally I think that maybe a render farm wouldnt be the best option in your case, maybe just split the render up into bits and render a section at a time.
MicWit
If the computers are networked, why would you want to copy the source files / textures etc onto both machines?
Two … or even more Blender’s can have the same file open, you can even render to the same directory, using the same base filename, as the frame numbers will make the file names unique.
Mike
Well, thats true, but if doing that, make sure you dont shutdown/reboot the computer the files are on 
Also, if you are doing something that needs large resources (mainly ram/hdd read), it may slow down if you have large textures or any large files involved with the scene. (on the computer the files are stored on if you arent rendering on it at the time)
MicWit
You could take a look at drqueue.
But for 2 machines that is hardly worth the effort.
Look for how to render in the console.
(blender -b -s 1 -e 100 stuff)
then create a batch file (.csh or .bat) with the commands in them
If you have one animation you can split them up manualy.
If you have lots of files you want to render then divide them over 2 batch files.
You can also take a look at B.U.R.P. ( I did not check it recently but it was mentioned at blendernation so must be going on something there ).
Keep in mind that with network rendering you need to setup your system so that every machine can find all the textures and lib files. On windows this means mapping a project directory as the same drive letter on all machine.
On *nix machine mounting the same share. Also the output directory should be findable for all machines.