In that case you got a bargin mate! Congrats! You see loads of 15"-ers going for around the £1350 mark upwards, and to get a 17" at that upgraded spec is awesome. If I didn't need the portability of my 12" PB I'd be very, very jealous!
That is a good deal congrats. I have to admit I am a wee bit jealous. I've been giving a 17'' PB some serious thought as of late. Its good to know that positive experiences can be had with purchasing on ebay. It would save a few $$$.
My girlfriend got a 12" PB from ebay and its 100% as good as from apple without any problems. When you buy something from ebay make sure you get a good seller, when i got the 12" PB for my GF i check the seller with +50 positive feedback, if you do your research you will have no problems. Congrats on your new Mac.