Subs/Amps....this could be bad...HELP!

Ok, my friend and i were going through some of his dads old stuff (he used to own his own car audio shop), anyways we came across a lot of miscellaneous speakers, tweeters, and a couple amps that looks like they've been around for a while. We found a somewhat new JL Sub (12W1-8) in a box. I already have a JL Sub (12W0-4) powered by an Eclipse 3650 5/4 amp. I asked if i could have it or if i could buy it and since we didn't know if it worked or not, i gave him $25 for it and that was that. I took it aross the street from my work to Circuit City to see if it worked. They tested it and said it did. I looked on EBay and found one like it for a little more (so i know i didn't get away with that big of a deal). I don't know much about subs and amps, but what's the difference with the amp i already had an the amp i just got? I know they have different Ohm levels but i don't know how that pertains to what i already have. I eventually want to get one more Eclipse Amp and a total of three JL subs so everything looks good, but will the amp i have now support both subs or can someone find me another Eclipse Amp that can power another 12W0-4 or 12W1-8 sub along with the one i already have?
Does anyone know what i mean?
Please help. :-(

the 12W0 will get louder, but the W1 IMO, sounds better

so can my amp power both and sound decent for now?

"IMO"?

IMO = In My Opinion