Thanks for the reply! Helps alot, i am actually getting the parts of my auntie's computer because she got a new one, all i know at the moment they are dell, but hopefully i'll have a reply in about a 3-7 days, thanks
Old Dell case is not suitable for gaming system, as the air flow is not optimized, unless your aunt's system was a gaming machine. Actually most major brand home PCs are not built for gamers, so it will have heat problem. My cousin had a Gateway machine with pretty good processor/GPU at the time, for mostly WOW , but eventually things went wrong when the heat damage accumulated. If you want to play games in high setting, you need a gaming case with decent air flow. And floppy drive is almost obsolete these days. Do you really need it? Otherwise, don't put it in your system.
But for the case, I think design is also important, for example, someone like me will be really annoyed by case with lightings and muscle-car type outlooks while many other people prefer them. So you better check amazon/newegg/microcenter and find a design appealing to your eyes, with 4 or more stars. I would recommend Antec Three Hundred, but even this low-budget case will be a little bit over your budget range. Again, customer reviews on those sites are really helpful.