For you, not-so-much the parent who doesn't even know her DVD player won't play BluRays.  Just because you get incredibly simple technology like automatic updates doesn't mean everyone does.  You would be surprised at how much something as simple as that confuses someone who has not grown up around technology.  Personally, a PS3 would be a terrible investment for his mom.

Will the store she bought them from not allow her to just return them or did she already open them all?

I would recommend this one,  I got it for my dad and he loves it.  Its has the latest audio codecs, a wide array of connection options, and its really easy to use.  

http://www.currys.co.uk/gbuk/sony-bdp-s370-blu-ray-player-04975489-pdt.html

You should try ordering it from amazon, it a much better deal and you get free shipping

http://www.amazon.co.uk/Sony-BDPS370B-CEK-BDPS370-Blu-ray-Player/dp/B0038M1UTW/ref=sr_1_1?ie=UTF8&qid=1292993783&sr=8-1

Right now there are a lot of offers in Argos, such as half price or save £50 and so on...

This is just a pick of a few of them:

http://www.argos.co.uk/static/Product/partNumber/5338784/c_1/1|category_root|Home entertainment and sat nav|14419512/c_2/3|15701169|DVD, blu ray and video|14419615/c_3/4|cat_14419615|Blu ray players|14419628.htm

http://www.argos.co.uk/static/Product/partNumber/9280072/c_1/1|category_root|Home entertainment and sat nav|14419512/c_2/3|15701169|DVD, blu ray and video|14419615/c_3/4|cat_14419615|Blu ray players|14419628.htm

http://www.argos.co.uk/static/Product/partNumber/0851620/c_1/1|category_root|Home entertainment and sat nav|14419512/c_2/3|15701169|DVD, blu ray and video|14419615/c_3/4|cat_14419615|Blu ray players|14419628.htm

http://www.argos.co.uk/static/Product/partNumber/0851503/c_1/1|category_root|Home entertainment and sat nav|14419512/c_2/3|15701169|DVD, blu ray and video|14419615/c_3/4|cat_14419615|Blu ray players|14419628.htm

Edit - you will need to copy and paste the URL into your browser, it seems that the direct links aren't working.

@ Twesterm, no she hasn't opened them but she wants Blu Ray now so who am I to stand in the way ^^ that and I'd like to see myself what a Blu Ray movie looks like.

@ Vetteman and Potable, thanks!! I'll have a look and compare those.

This Sony was voted best for under £150 by What Hi-Fi - at least according to John Lewis where I like to get electrical goods from:

http://www.johnlewis.com/231017516/Product.aspx

I'm sure you could find it for less than John Lewis though.  Samsung and Panasonic also have some very good sub £150 BR players as well I believe.

Sony S370

Not only this, it won overall product of the year in reader's award.