Have you considered it may not be the computer and it could be the operating system you are using. Windows is a far from stable operating system and is prone to problems as a quick read through these forums will show.
All operating systems have problems, But some are better than others. just because the majority of people use Windows it don't necessarily make it the best.
Like you I used to get very frustrated with my computer until somebody introduced me to Linux and now I wonder why I persisted with Windows for so long.
I know this is not going to directly help the problem in hand and 'greysts' advice is worth a look. But if you are in it for the long run its an angle worth considering.