[G4] chickened out

[thekirkline1941 at verizon.net]

Thanks again for the help in installing the PCI card and new hard drive. However, I chickened out when it came to putting in both 500 GB drives. Someone cautioned that that might be too much for the power supply. Consequently, I only installed the one drive and partitioned it into two 250 GB. This should suffice for a while. However, per the following--- "OR, another way to copy the contents and have the  
new copy as a bootable drive is to use Apple's own program,  
DiskUtility, and use the Restore function by selecting your original  
drive as the source and the new drive as the destination for the  
restoration."---I did just that. I must have overlooked something or did something incorrectly because now, when I delete something from my original drive, it is deleted from the backup as well. What should I do to prevent this from happening. Thanks.

Jim Kirk