Quote from iJustinnn
Speaking of which, I have a laptop with about (I think 250 GB?) but my minecraft says I only have about 450 MB and I'm always lagging because I'm at about 300 MB is there a way to up my MB to make it like 5 of those GB's and not lag as bad? P.s. I'm very bad with computers :L
Its referring to system memory or RAM. RAM is the type of memory used by computer applications. your 250 GB is just Hard disk memory. No matter how big your Hardrive is, if your RAM is small, you're not gonna be able to do much with your PC.
Go to Start. Right click Computer, then click Properties. It will show you your PC's Processing power and available RAM.
Follow instruction here http://www.minecraftforum.net/topic/1395030-tutorial-allocate-more-memory-for-minecraft/ to allocate memory to your minecraft.