As usual, the Dell specs for that laptop are as clear as mud with the different options you can have.
The biggest issue you'll have with blu-ray playback, IF your machine can handle it (and I think it can), is the software for playback and the specs that needs. I would recommend ArcSoft TotalMedia Theatre 5 as the software you actually use as it needs a lower spec than other stuff and your processor will handle blu-ray with the Arcsoft player. IF you have the Intel graphics on your laptop then it should be the GMA 4500 MHD which can do full 1080p HD so should be able to handle blu-ray. 4gigs RAM is plenty for playback.
So I would reckon you can get yourself a blu-ray drive and enjoy full HD on your laptop, using the
Arcsoft Player
Enjoy