upgrade HDD for Thinkpad X61

I bought a new 2.5inch HDD for Thinkpad X61. This time, I didn't survey much and just went to 光華原價屋. I had already had a decision in my heart. That's either 500g 5400rpm or 320g 7200rpm. So I just went into one store and bought a HDD. When we communicate about spec. of HDD with staff, he wasn't familiar with spec. of X61. I had to make decision by myself. A 500g HDD has larger capacity but a 320g HDD got higher transfer rate. The prices of both are around NTD3000 but a 320g vibrates more seriously from operation. I hesitate to choose one of them. but a WD3200BJKT is my final choice. I bought it home. It's good.I imaged the original HDD data to a new one by Acronis True Image WD Edition provided by WD. I am using the new HDD to type this paragraph. My laptop performs as efficient as a desktop now.