Hi Blackicicle - like the other reviewers I suggest losing the sound. Sites that load a sound file on initial open can be an embarrasment to people browsing from their office PC who maybe should be doing other things...
Similarly - the mouse trails are just irritating. I get the impression your friend has taken some delight from finding that he can do it - but just because he can do it, doesn't mean he should!
For a site selling relatively expensive speciality technical books and test equipment I'm not sure the jokey approach (with Frankenstein and 'don't mess with high voltage') really works - I think a more staid presentation would be more appropriate.
The standard 2 col + banner layout is a good choice for this site though - makes it clear and easy to navigate - but the site has a horizontal scroll bar at anything below 1024 x 768 resolution - where most try to support down to 800 x 600 without horizontal scroll.
I like the dappled background - it's not too prominent and is easy on the eye - but the grey banner seems a bit dull. A shade of blue seems an obvious choice for an electrical site - maybe with a little red / yellow to add a spark of colour.
The typeface on the banner is heavily pixellated on my display which creates a kind of 'poor quality' impression - I would suggest using text for this - both to display better and for search engine optimisation - but I don't know how much control you have with Sitebuilder - which is what the site appears to be done with.
My main advice to your friend would be first to take it a bit further with Sitebuilder in terms of getting the structure and content sorted, but to plan to move to XHTML / CSS later, which will enable a more professional finish and be more search engine friendly. There is a nice simple 2col layout at
http://bluerobot.com/web/layouts/layout1.html