Note that the USB card is going to be a lot slower than the internal SSD. If you can afford the 256GB SSD I'd go for it. Granted, I did manage for the last 2 years to cram both OS X and Windows 7 onto a 128GB SSD, but I didn't have an 8GB game on Windows. Note that the 128GB SSD is only 121GB, while the 256GB SSD is 251GB (meaning you have 130GB more space).