If you knew Spanish as a second language, would that help any

learning Arabic?

at least for word recognition--not in the same way it would if you were learning Italian or French. But, since you've already learned a second language, I would imagine you are used to the mechanics of grammer, syntax, etc, and that might help.

I don't speak Arabic (always wanted to for some reason, that and Russian; I think I have a thing for learning alphabets or something), but I understand it's difficult.

Found this link: http://www.al-bab.com/arab/language/learn2.htm
ETA this link: http://www.slate.com/id/2120258/

The Foreign Service Institute classifies Spanish as one of the easiest language for English speakers, along with Italian, but Arabic as one of the hardest, along with Japanese, Chinese, and Korean.

If you knew Hebrew, it might be some help, since Hebrew is actually a related language, but Spanish is much closer to English than to Arabic.

as Arabic is in a completely different language family than Spanish or English.

Although, as already noted, once you've learned one foreign language the next one is generally easier, although that may really only apply to the next one being again in the same language family.

Spanish is in the Italic branch (which consists mainly of the Romance languages French, Italian, Spanish, Portuguese, Romanian)of Indo-European while English is in the Germanic branch (English, German, various Scandinavian languages)of that same Indo-European language family. Arabic is in the Semitic branch of the Afro-Asiatic language family, as is Hebrew. (thank you Google and Wikipedia) They are both very different from English or Spanish.