I did this as a post on my blog but I was too slow turning on cloudflare (I keep it off normally as it mucks up my xmpp server) so the server crashed so i'll post a cut down version here in the forum.
There are a couple of gotchas when making a bootable sd card under windows that might catch the unaware out.
The first gotcha is that although your windows computer has a builtin sd card reader/writer it probably won't work for making bootable sd cards. Although the builtin reader/writer works fine with sd cards from your cellphone or camera it won't when trying to make a bootable sd card. I suspect it's something to do with a dumbed down controller chip in builtin readers that don't support writing to the lower areas "partition table", MBR... (yes i know sd cards don't really have such things but using the terminology maks it easy for people to understand what I mean). The 0 to XXXX part of the SD card. I know that the ricoh sd card reader/writer in HP laptops definitely have problems and other makes of builtin reader/writer and laptops do too although I can only state for a fact from personal experience that the ricoh/hp combo do.
So if you are going to be using windows to make a bootable sd card for your raspberry pi you should use a USB SD card reader/writer. I've not yet found one that doesn't work for making bootable sd cards.
The second gotcha is that sd cards are not like harddisks or other r/w media in that in normal use they can only flip a bit from 1 to 0 and not vice versa. deleting doesn't reset any 0 bits back to the initial state and doesn't allow you to reclaim the space. if you are going to use an sd card you have previously used then you will need to format the sd card before use. You shouldn't use the builtin windows formatter as although it will say it worked and has sort of worked it hasn't actually set all the bits back to their 1 state. To format an sd card under windows you should use a USB sd card reader/writer and the panasonic sd card formatter http://panasonic.jp/support/gl.....index.html
If you use the sd card formatter, something like Win32DiskImager and a USB sd card reader/writer then you should have no problems making your bootable raspberry pi sd card.