It has screen big enough at 17.3 (1600x900) HD, 500 GB storage (twice as much as your requirement), Blu-Ray R, and a dedicated graphics card (1000 MB Dedicated graphics card, ATI Mobility Radeon™ 5650). Processor is a 2.1 GHz AMD with 4 GB RAM.
It's a little over your price range at $799, but might be worth a look. What do you think?
The Acer from Walmart looks like a pretty good deal, especially since you'd get a discount on it. I doubt the battery will last more than an hour on the 540M, but you can expect 2-3 hours on the integrated graphics. If you're fine with that, go for it. The other two laptops you listed probably won't run RIFT quite as fluidly.
Don't forget that SB laptops with comparable GPUs will perform noticeably faster for many games though.