There are a number of solutions that can give you a bootable USB drive.
- Use Windows AIK to build a bootable version of windows and put it onto an external hard drive/thumb drive, however I find this one probably the most convoluted of the lot.
- Use a program called WinBuilder which has a project called Win7PE_SE which works awesomely.
- Using BartPE which uses a cut down version of windows XP to boot into - which I used for a number of years when working as an IT admin.
- Using Clonezilla open source project which I haven't had a lot of experience with but it seems to work well
Any of these options can help you make a portable version of an OS that you can boot into. To capture the image of your computer and restore you must firstly learn how to sysprep
a windows computer. Sysprep will allow your computer to be captured and restored time and time again - even on different hardware makeups. Once you know how to do this you can use a number of programs to capture/restore your computer's image. Note: Ensure you have an external hard drive large enough to capture the whole disk of your computer.
- imagex is Microsoft's solution for capturing and restoring images
- Clonezilla that I noted above is for just this
- There was another I think was called RapidDeploy that I used all the time but I use WDS now so I've long forgotten where I got it.
There are heaps of articles all over the web and hopefully the above can get you started and then they should help you out.