my budget is : 500, but for the price i pay i sorta expect stunning graphics with absolutely nooooo lag
Well, take it from my personal experience. My old laptop had 6 gb ram, a 3.0 ghz gen 2 i5 processor, Intel Integrated HD 3000 chip set graphics, and cost ~ $600.
OpenBVE lagged like hell on it. (average of 4-6 fps with the new R46)
My NEW laptop has slightly less hard drive space (500 gb vs 640 gb), only 4 gb ram, a 3.2 ghz gen 3 i5 processor, and NVIDIA's GeForce GT 730M discreet graphics card. It costed only ~$70 more (tax included).
OpenBVE runs beautifully. (average of 17-20 fps with the new R46).
I'm going to tell you the hard truth. You can't get a computer with the discreet graphics spec you want for your budget, unless you're sacrificing much needed Hard Drive capacity, or RAM, or you're getting a shitty processor. You want something that performs? You'll have to sacrifice a little more $.