Subs, or Change stock speakers

I don't know which to get, should i change out my stock speakers or should i get these two subs from my friend for my car. Which do you think I should do first, either way I going to do both after a while, but what should I do first?

I was also wondering if these are the subs my friend is giving me,
http://www.circuitcity.com/detail.jsp?c=1&b=g&u=c&catoid=-8871&qp=0091031650516&oid=89657&m=1
Would this Amp do a good job on them and have them play well?
http://www.sounddomain.com/sku/PIOGM5000T

The amp and sub go together ok I think - the sub is rated at 150W RMS (600W peak) and the amp will put out 125W RMS... Personally, I'd use different components, but if that's what you have to work with it'll be fine...

As to what you want to do first - your call. I'd change out the stock speakers if they're ratty to begin with - probably a better chance your system will sound better most that way (better even still with the sub and amp, but the biggest improvement by getting a good set of mid-bass speakers)...
My $0.02... see what the others think...
Good luck!

I would get 2 new components, run them off a 4 channel or 2 channel amp depending on your budget. Mid bass can sound nice for bass for a while. Just don't abuse it