Though the Recovery Manager is handy for some maintenance tasks it shouldn't be required.You can always download drivers from your support page at HP if needed. The F11 to do a Recovery should still work since the files are there in the D partition.
However if you didn't burn your Recovery Discs before removing Recovery Manager it might be a good idea to order them from HP. In the event of hdd corruption or a failure requiring replacement you will need them to boot the machine to reinstall Windows.