.Ass subtitle with fuzzy fonts hardsubbed on HD mp4 video file.

[OutStanding]

Hi.
For about 4 days I'm trying to hardsub / convert -VirtualDub didn't accept it as an mp4- a HD mp4 1080 video file (one for the moment), downloaded from youtube, to realize that.... I loose quality or.... it takes even DAYS to finish that job.
Now, when you lose about 3-4 hours per day, your eyes hurts, your anger accumulate -it's a f.... old machine wich tends to block very often- and you only stay tuned with coffee perfusions, you'll know what I'm talking about.
I have installed on this machine, which runs on XP, these app. : - AVI ReComp 1.5.5, Avidemux 2.5, AviSynth 2.5, DivX codecs, FfdShow 1.2.44, Freemake video converter 3.0.2, x264vfw - H.264 MPEG-4/AVC, Xvid Video Codec and XviD4PSP 5.10.289 just to test various hardsubbings.... blindly.
As I said, fort the last 4-5 days keep trying and trying to hit perfect combination of codecs & configuration in order to hardsub 14 videos.
Now, this is my last resort. Didn't want to bother any1 with my small pbms., but.... somehow, I think that are in interest of us all. You'll see, NO matter if you could find time and know how to help me or not.
Did a lot of documentation to discover that.... I really don't know much about video, audio,.... IT things, so.... do NOT assume that I know what you mean.
I digged on entire net -youtube has one or two files about this pbm. solved by MeGUI-, but.... I think I need a biography and some1 who can guide me into videoediting world.
I made this intro. cause.... I'll never understand, nor could help any1 if I'm asked cause.... I could not tell that pers. smth conclusive, therefore I want, aside the solution, to help me to understand frame by frame this.... videoediting process.
At least what suites my needs.
So, what app. should I use and what codec (with entire configuration) to finish my job ?