In the under $500 range, I manage to pick up a Samsung NP305E5A-A07US with Windows 7 roughly 2 months ago. This laptop came with a quad-core AMD A6 processor, and is upgradable to the newer AMD A10 quad-core processor (which I have not done yet). It also came with 4GB of RAM, I DID upgrade that to 8GB since RAM is inexpensive these days (the extra 4GB was roughly $20).
I also have a MacBookPro (w/ Intel i7 processor) that work has provisioned to me. While I will agree that the MacBookPro (MBP) is a very powerful and "well built" laptop, it is also very heavy. It's aluminum chassis construction is nice and the display is top notch (quite possibly the best I've seen on a laptop). However, it is also mega expensive (even the REFURBISHED units exceed $1500), and it doesn't even have a full keyboard.
I bought my "cheap thrills" Samsung laptop because I recognized a need to delineate work and play computing, and the Asus netbook that I have is too underpowered and too small to use for games. The battery life matches or surpasses the battery life on my work's MBP, which is 3'ish hours on full charge. So far, the only thing I've found lacking on my Samsung is the display. It's plenty good. However, my gripe with the display on my Samsung is grounded in the fact that I've been using a MBP (with it's exceedingly awesome display) for work over the past year. So, seeing the short comings of the Samsung's display is more apparent than if I had never used or seldom used a MBP.
I think this laptop will last a while, especially after upgrading the processor to the AMD A10 processor, and upgrading the HDD to a SSD. Of course both of these upgrades will happen later on down the line. The biggest performance boost will be switching over to SSD as that will provide a 10x boost in disk performance, and theoretically reduce battery use.