Hi
Is ther any specific requirement which forces u too go for 11.3(2) for your box ??
since 12.3 is already there for quite sometime and has GD versions too which would help u out for long run.
still if u want to download u need to find out whether any bug report has been announced by cisco for this particular version,if not u can then verify the memory space and the flash size required to download the file.
For feature navigation do use this link ..
http://tools.cisco.com/ITDIT/CFN/jsp/index.jsp
for downloading the ios (just navigte from lan to ios)
http://cisco.com/kobayashi/sw-center/sw-lan.shtml
do remember u nedd to have valid cco id to do the same..
regds