For the Sikh names Hardeep ("light of god") and Harpreet ("love of god") try this site:
http://www.indiangyan.com/books/childcarebooks/baby_name_scripture/sikh_names.shtml
Couldn't find "Arminder", unless you may have misheard it and it's really "Amrinder" (which appears much more frequently in 'net searches.) An apparent variation -- "Amrindra" -- means "eternal India".
-- Nanaea