Installing 2.0 Sp1 - Setup Error

I�m having many problems during the instalation of microsoft net framework. First of all this occur cause i was trying to install NET FRAMEWORK 3.0 on my computer but the instalation never ended and it give me some errors, so i uninstall every version of the program trying to reinstall them again (i read this may be a solution (i use add/remove programs and a clean up tool specified for removing net framework)), first i try installing 1.0, but a message says that i already have it installed, then 1.1 which i could install fine, then the SP1 for 1.1 says that i need version 2.0.5556 in order to install this service pack, then i try to install 2.0 but an incompatibility error appears referring that i may have installed " framework 2.0 sp1" (wich i don�t), then i try installing 2.0 sp1 but i get a "setup error" nothing else, same when trying with 3.0.

i have try different things like starting/stopping msiexec (on safe mode), installing and removing net framework several times or trying to install IIS (wich i couldn't cause i dont have the original windows cd) as possible solutions, but this problem is driving me crazy! Is there a solution like uninstalling all, installing all again without format? i think it maybe has something to do with file extensions missing, i read something about MSI files, but im not share.