I have a set of windows icons (eg.folder icons, drive icons, network icons, file icons) that I have installed with IconTweaker. My icons show on my desktop and in explorer. Is there a way to make dopus use these icons I have, instead of the XP defaults it uses? 
As far as I know all "custom" icons have worked with Opus for some time now...
hmmm well SOME of them are working, like the icons for My Computer, My Documents, Recycle Bin, Control Panel, but icons for folders, drives and filetypes aren't. - they all work fine in explorer 
It may depend on how IconTweaker changes the icons. There are a few methods and some only work on Explorer. (Some seem to actually target explorer.exe when all that's really needed is a registry setting, for example.)
Have a look at this FAQ for some details and the registry settings for changing the folder icons (very simple to do by hand to check that it works):
aha, I was using 9.0.0.0, finally updated, with my painfully slow connection, and I see all the icons as they should be. Thank you for your speedy replies, kind siRS! 