Is it a way to boot my pc up using my second harddrive?

I just added the hardive from my hp laptop to my lenovo desktop so that i have access to both hdd's, both run windows 7 home. Is it any way i can boot my desktop up using my 2nd hdd so that i can access the programs from the added hdd and use my tower as my laptop? (In order to use the programs from the laptop hdd and access saved passwords, etc.)

Yes. Select the correct boot order in your BIOS settings. Make the drive you want to boot the first device in the list. Obviously you'd need to install all the correct hardware drivers for your PC and removd those you installed for your laptop.

Mo. It would load all the wrong haedware drivers and continuously boot loop or blue screen crash. Worst casw it could over drive the video card and destroy it or the monitoe or both. If you coud get [ast all that it would see the change of machine and report itself to Microsofy as pirated and deactivate.