Sadly, software doesn't always work 100% with all hardware configurations, as far as I can see, you're just a very unlucky sod. I've had steam on 3 different computers, one 10 years old, one 8 years old and one 2 years old, it runs beautifully on all of them. No glitches. Its even miraculously managed to stay online when my wireless cut out, MSN, GTalk and browser didn't...an amazing feat I think.

From what I've always understood, average experience is good.
Have a problem with software or you're unable to use software you've paid for, then talk to the steam customer support, it exists for a reason, they might actually be able to help you or offer a refund. If not, then nag them.
However, I might recommend brush up on your written English, not meaning any kind of offense, it's just I doubt customer support will be so sympathetic if reading your email takes effort.