It's all in a new user account, created by the migration. See the last few lines of OS X Lion: About Windows Migration Assistant
You mean move it from one user account to another? If so, while that can be done fairly easily for iTunes, it's not so easy for other things.
If you created an account when you set up the Mac, then migrated the HP user account, do you really need the original Mac account anymore? If not, use that account to give the HP account Admin rights (via System Preferences > Users & Groups), then log off, log on to the HP account, delete the Mac account, and just use the HP account.
If not, the safest way to move the iTunes library is to use the HP account to copy it to the Shared user folder, then use the Mac account to copy it from the Shared folder to the Mac account. See Transferring files from one User Account to another, especially the blue box there.
Since you transferred from a different computer, also see iTunes Store: About authorization and deauthorization.