Are you talking about installation files or the drivers themselves? Drivers wouldn't go to C if your operationg system runs from a different HD/partition. They install into your System directory wherever that might be.
If the ATI zipped file unfolded itself into your C drive - just point the installer to the right directory when you install the drivers - makes no difference where the installation files are located.
Which version were you trying to install anyway? I try to keep with the latest and haven't had any probs yet (C=W98SE/D=junk/E=more junk/F=W2K)
p.s. if you try to uninstall them under Win98SE - it won't do a thing, you didn't install them there hence they "don't exist" form Win98 point of view.
Dual boot can be confusing but think about it as 2 diffrent machines just sharing the same box - programs installed under one won't run under another etc

[ 06-11-2001: Message edited by: -lynx- ]