There is barely any difference in price between the Petrol and the other two drives I mentioned, yet a dramatic difference in performance. Even though the access times of the Petrol - through virtue of being an SSD - are much better than HDDs, the read/write speeds are very slow; I have a 3TB Seagate on a SATA2 port that posts better speeds.
I really cannot understand how you can recommend the OCZ Petrol to the OP when for just £2 more you can have a drive that offers up to 5x the performance. That's really bad advice.
My point was that the performance doesn't matter. Even if the Agility was actually 5 times quicker (it isn't, outside of synthetic situations) you wouldn't notice any difference between the two drives. It's like trying to tell the difference between a graphics card pushing a game at 500FPS vs one that does 1000FPS.
When dealing with small files, both drives will be imperceptably quick on home workloads. When dealing with large compressed files (Game textures, Videos, Music, Photos) the Agility is practically the same speed as the Petrol (check out AS-SSD benches if you want proof)
For £2 you may as well upgrade (I didn't see the TWO offer), but for the more usual 15-20% premium there's no point. I'd expect the petrol to go on offer shortly and drop significantly below £1/GB.