Bitcoin is supposed to be safer, since it has way more hashing power united under it's name. Of course this doesn't help against bugs in client or miner software, but since it is open-source software I would not worry to much. To be more sure about your virus maybe upload it to this site: virustotal.com Sometimes anti-virus does give false-positives, so checking it against various other scanning engines is wise (which is the purpose of virustotal). Also be sure to only use the official site (litecoin.org) for downloads (or compile the source yourself )

I like the aspect of litecoin that it has faster transaction validation, since it is too long on bitcoin.