PC Magazine, PC World, CPU (Computer Power User), Official
Windows XP, Macworld, Linux, Maximum PC and HWM.
PC Magazine and PC World has a Singapore version and can be bought
from newsstands or bookshops.
Macworld are in major bookstores, particularly Popular.
CPU, Official Windows XP, Linux and Maximum PC might have to spend
some time hunting. They are not always in Singapore.
Gaming magazines I can't really recall the names, but the names are
pretty obvious. Gamers or something similar. Popular bookshops have
them.
Gadgets wise, it's mostly related to photography and some
entertainment stuffs like speakers. Major IT magazines do write up
on them, but not as detailed. Again, at major bookstores.
Other rarer magazines will have to hunt some smaller bookshops
around neighbourhoods or those that rent out books. I saw a Hackin9
magazine around my area. Hackin9 is about security and
networking.