You can make the windows partition the boot partition and remove all the others. It is risky though!
First create a System Recovery CD (from the Backup & Restore applet). Next use a third party partition tool from a boot disk and delete the partitions you don't want (I have never seen an OEM recovery partition that cannot be deleted). Resize remaining partitions you left behind to use the space.
Next boot from the Windows Recovery CD and choose repair your computer. Once into the repair tools menu use
bootrec /RebuildBcd
from a command prompt
That will find your existing Windows 7 installation and rebuild the BCD Boot folder on the Windows partition (since there isn't a boot partition).
Three points:
1) I don't recommend this (better to keep a separate boot partition IMHO)
2) Make sure you have a whole drive image before doing it in case anything goes wrong.
3) Don't blame me if it goes wrong

Originally I had Windows 7 dual booting with Windows XP - the boot partition was XP - I used this method to remove the XP installation and expand 7 to the full disk.