Seagate Drives giving errors in HDTune and Seatools

[mindrot]

Hi,

I have two 500gb Seagate (ST3500320AS) SATA II drives in my PC. They are probably both around 2 years old (both are secondary backup drives, my C Drive is a Hitachi Deskstar). One of them was RMA'd twice when I originally purchased my PC from Overclockers. First drive packed it in after a couple of weeks and then the replacement did as well .

I've tested both with HDTune and Seatools. One has come back with errors when I did the Error Scan in HDTune and has also failed some tests in Seatools

I also get these two warnings in HDTune on the erroneous drive:
(5) Reallocated Sector Coount 100 100 36 628 warning
(C5) Current Pending Sector 100 100 0 1419 warning

And the I get this warning on the other Seagate:
(0A) Spin Retry Count 100 100 97 1 warning
EDIT: I had no errors on this drive when doing the Error Scan, just the above warning.

Can this be fixed of should I just replace them?

Any help would be great.

PS: I'll probably replace the one with errors for now. I was considering going with either a Hitachi Deskstar, a Western Digital drive or possibly a Samsung SpinPoint? Possibly a 1TB drive instead.

Thanks, any help or suggestions would be most appreciated.