I am performing a simple copy-paste backup from system to an external USB 500GB Seagate as I periodically do for my personal data.  This time however the copy speeds have shown as low as 600 bytes/second to 5KB/second yesterday, and now the speed runs anywhere from only 2.33KB to 35KB even when transferring individual subfolders instead of the whole root at once.  I performed a system restore today resetting to 5 days ago in case of malware. 

Also for reference, at the bottom of the list of processes in Task Manager shows a line titled 'percent of the time the CPU is idle' with the number reading between 96-99% in the CPU column.  I consistantly use Trend Micro PC-cillin and also just downloaded and ran SpyBot, both with zero threats found.  I show 87 processes and 35-55% physical memory.  But, from what I read here the low % physical memory may just be JIT and pre-fetching and therefore normal - or not.

Numerous calls to Dell Tech produced no improvement and just their conviction it was 'a software issue', and conversation with Dell Software Support had them directing me to reinstall the OS to solve everything. 

Questions:  Is there a diagnostic to reliably increase performance for backup?  Also, I admit no familiarity with the nomenclature for what I consider the excessive number of processes running.  Is there a trustworthy list of exactly which can be eliminated without upsetting the system?

Thank you,

XPS420 2 Quad Q6600 2.4GHz 2GB Vista Premium