Is my hard disk dying?

This is my first post so sorry if the answer is obvious to you.

I have a Dell Studio 1555 laptop, Windows 7 (Ultimate - 64 bit), which is running v.slow. I have run chkdsk /f /r and it has repaired a bad file but I am getting errors when running Dell disk hardware tests:-

1. Read test
Error Code 0f00:0232
Block 35020160 interrupt request did not set in time.

2. DST self test
0F00:065D

When I run Paragon Disk Backup tools it tells me there are minor disk errors.

Current disk is Samsung HM 320II (300 Gb SATA), should I buy a new (larger) disk now and if yes then what is recommended? I hope to use Paragon recovery to copy data over to new disk.

Many thanks