I have a Lenovo W520 which has discrete graphics, 32GB of RAM (added aftermarket) and it is a beast. I also upgraded the HDD to an SSD and that is something to do right.

Some minuses are that the bluetooth quit working with Windows 8, although I got a USB bluetooth dongle. Also I got the dock for the W520 and found it doesn't work ~quite~ perfectly in terms of the USB ports realizing you just plugged something in and connecting on the first time.