No, you can't normally "use" Linux while booted into Windows. However, you may be able to read files from the Linux hard drive partitions using a tool such as
Explore2fs or
YAReG. If you wish to use Linux commands while in Windows, you might find
Cygwin useful. You could try
Cooperative Linux which claims to be able to make Linux run inside Windows without full virtualisation, but I've never tried it myself so have no idea if it's any good.
The other alternative is to run some kind of virtualised environment in Windows/Linux, and install the other OS into that.