VLC is excellent, and as Leshy says, will play pretty much any format you can throw at it, and has no worries about playing DVD's from other regions (something the actual windows laptop gets stroppy at). I'm a huge fan of Irfanview, which is a picture viewer (with video bolt-ons) whicha gain, handles a huge amount of formats and costs nothing.
However, since you can buy a perfectly decent Blu ray player from one of the big four brands for just under £50 if you shop around (I spotted a J4500 Samung in Sainsbury's the other day for less than £50), you could go that way, or get an external blu ray reader for less than £40.