Raptor + another HDD

[mis33]

I am building a new Q6600 PC and I am looking for hard disks. Is it still a good idea to install a Raptor (74 GB or 150 GB) as OS drive and another higher capacity HDD (WD-750 GB) for data?

The reason I am asking is although the Raptors are still the fastest, the newer drives are catching up. Furthermore, the Raptor is SATA and the other drives are all SATA-2.

 

[mis33]

My question is more on system performance than system configuration. Using Drive Image, I will buy an external HDD for backup.

To be more specific, would I see a big difference in performance in these 2 configurations:
1. Raptor + WD-750
2. WD-750

Two years ago, Option-1 was definitely the preferred configuration. Since OS is used all the time in a PC, it makes sense to install it in a faster drive. Seems to me that although Raptors are still the fastest, the other newer drives are catching up. According to reviews, the new WD-750 is fast.

If there is no big performance difference, I would prefer using one single WD-750.