Problem playing ISO's on 3.03OE-B CFW

Hi, I have a phat psp TA-082 that I downgraded to 1.50 then upgraded to 3.03OE-B.
I haven't upgraded since then (over a year ago) and now I want to play some PSP ISO's.
I have a Final Fantasy 1&2 ISO, it appears on my memory stick menu but when I try to play it it says
"The game could not be started.(80020321)".

I believe it's because my psp CFW is too old, anyone know the versions I could upgrade to and still be able to play firmware?
Also which ISO's work with which CFW?

THANKS

That FW doesn't have no UMD modes.

Put a UMD in or update to 3.90 or 4.01

Can I still play homebrew (nes, snes and all the old games and emus) if I upgrade to 3.90 CFW?

yes, you never really lose anything when you upgrade, you only gain

Is there a specific order I have to upgrade or can I just go straight to 3.90?

I reccomend going 3.03 > 3.52M33-5 > 3.90M33-3

I only see 3.52M33-4 , there's no 5 in dark alex's site

Okay then. Update to it.

Just tried it, said it wasn't applicable to my version or it was already done.

I haven't changed firmware in over a year, if I remember right all I gotta do is unzip the files and put them in Game150 right?
then run it in my psp...correct me if i'm wrong because I don't know if it is.

You have to update to the Original 3.52M33 first.

yup

says, "Loading 1.50 firmware...file 150.pbp couldn't be opened."

I did put a 150.pbp on my game150 folder

You put it at the root along with 352.PBP

Renamed EBOOT.PBP into 352.PBP and placed it on the root along with 150.PBP

nothing shows up in memory card

Did you download the installer?

I only downloaded the firmware.
Where do I find the installer? I tought it was the same thing