Seagate 2TB vs WD 2x1TB Raid SATA3, Which one?

I have a little dilema on which drive I should get. At the moment I have storage issues.

I currently am using 2x300gb WD Velociraptors one as storage and other as OS.
I dont want to put them in the cupboard once i get a bigger drive so I am planning to put them in a NAS.

The plan during the winter sales is to buy a SSD anywhere from 64gb upwards, depending on price etc..
The SSD will obviously be used as the OS drive along with applications such as lightwave, photoshop, dreamweaver etc...

The second drive which is the problem, is going to be used as a game drive. The only reason for this is because of steam and my crappy ISP "virgin media" 5gb download cap.
Getting really tired of seeing it saying 2 mins to go then cap sets in and say 1 hour left

Choice is between 2 drives.

Seagate Barracuda XT
WD Caviar Black
I can either go with 2TB Sata3 single drive or go with 2x1TB Sata3 drive in Raid 0 config.

I dont really care about the price of thses drives just the perfomance the the likelyhood of failure (never had raid before).
What is your opinion?

Between the Seagate and the WD, it's really a coin flip. They are both great products, and you will be happy with either one.

Coming to RAID - Do NOT go with RAID0 because RAID0 is striping which means that the data is striped and written on both drives. This means that if you lose one drive, you lose ALL data on both drives.

Instead, go with RAID1 which is mirroring. If you lose one drive, you have the other which contains ALL data.

This will explain RAID quite well - http://en.wikipedia.org/wiki/RAID