VA-503+ MB copying partitions from HD1 to HD2

Hello,

Hope there's a guru(s) around.

I've purchased two WD80GB drives in the past. Recently purchased
a WD120GB drive. All drives are 'JB' type. All 7200RPM rabbits.

Using 'Copy Commander' I copied entire WD80GB to new WD120GB. Transfer
rate approached 200MB/min. Same applied when copying WD80GB to
secondary WD80GB. Satisfied with that transfer rate.

Recently, I tried to use Copy Commander to copy WD120GB partitions to
secondary WD80GB drive. Transfer rate was surprisingly only 75MB/min.

Any clues/suggestions at troubleshooting the cause?

CPU is K6-550, Memory is 392MB, MB is FIC VA-503+ with JE4333 BIOS,

UDMA is BIOS detected for each HD,


Thanks for any replys,

G.