New hard drive

I am changing my old HD Samsung SpinPoint P80 SP1604N - hard drive - 160 GB - ATA-133 in my Compaq Presario SR1617CL Desktop PC. I have looked and thought these 3 HD's might work as a replacement. 1.Western Digital 320 GB Caviar Blue PATA 7200 RPM 8 MB Cache Desktop Hard Drive WD3200AAJB, 2.Western Digital 500 GB Caviar Blue PATA 7200 16 MB cache WD5000AAKB internal 3.5" hard drive, 3.Western Digital 500 GB AV PATA 7200 RPM 8 MB Cache AV Hard Drive WD5000AVJB, I think with my limited knowledge I will stay with IDE/PATA HD even though my motherboard does have SATA capabilities. I would appreciate some input I do not know if going from 2MB cache to 8 or 16 is a factor in replacing old one or if the AV Hard Drive WD5000AVJB can be used. I also am planning on putting which ever HD I get in as a slave to start, then download BIOS and XP pro after which I was hoping to use new HD as main and keep old HD as a slave after restoring to original format, if this is also possible. I also will tell you I have replaced sempron processor with athlon 64, and now have 4 GB memory. Every time I have asked questions I have got wonderful help in the past, thank you all.