"original equipment manufacturer"
its basically the same thing as retail, except it doesn't come with the packaging, CDs, fancy box, etc...
sometimes OEM is the better option, like in the case of hard drives, and sometimes video cards.. BUT.. when it comes to CPU, retail is a lot better because it comes with a heatsink fan, and a better warranty. the OEM cpus don't come with the heatsink or fan..
the system you have now is pretty much the same as your previous one, except 1) its compatible 2) much better memory
it looks good.
oh and as for gst/pst calculations... just use your computer calculator
to calculate gst on $10, just go 10 X 1.06 = 10.60.. or if you just want the tax, and not the total, go 10 X 0.06 = 0.60
i don't know pst where you live.. but here in bc its 7%, so if i was calculating tax, i would multiply by 1.13
just converting percentages to decimals