Did you check the link? You can see I'm not giving you wrong information, it's there in black & white.
You bought it brand new with 64-bit Windows factory installed?
I suggest you contact Dell to ask why it had an OS pre-installed on it that's not officially supported according to their own drivers page for that model.
Well I didn't buy it really. It's quite old (5 to 6 years ) and I'll be changing it in an year or so. My dad used to work on it and when he got a new laptop, he gave this one away to me. So I don't have any stuff that comes with it because he got it for work from his office too. Welp, I think I'm screwed here.