Iphoto update help, please please please

Hi all. I have a lovely old eMac, it's running quite slowly but still does everything I need it to.
I have iphoto 4.0.3 on it and tried installing a newer version this evening and it gave me the following error message as I was attempting the installation
[IMG]file:///Users/Claire/Desktop/help.jpg[/IMG][IMG]file:///Users/Claire/Desktop/help.jpg[/IMG] "You cannot install iPhoto 6.0.5 on this volume. An eligible iPhoto application was not found in the location ? Applications/iPhoto.app"

I now have no idea what to do and could do with some advice please. I've had the emac for a few years now, it was given to me by my fiance who used to do all the technical stuff with it for me, we're no longer together and I want to manage it myself if I can, with help :0)

Thanks in advance

Where did you get that update?

The only updates you want to run on that eMac are the ones under the Apple > Software Update... menu. Anything else and you'll run into compatibility issues.

It's way past its "use by date" and you should just let it do what it does until it dies.

On a Mac that age, I'd stress, KEEP A CURRENT BACKUP!

Hello, you can't update iPhoto4 to iPhoto6 without paying for it. Well, legally anyway. Hence, the error message. Here's a link for the iLife 6 specs if you're interested. http://support.apple.com/kb/HT2675

Thanks to both of you for replying.
I am backing it up and will remove as many pics from it as poss in the hope that the computer will last a bit longer.
I can't afford another Mac, not even a second hand one, and can't imagine going back to using a P.C (shudder) so I've got to keep this one alive for as long as possible.
Would an external hard drive make a difference to the running speed/life of the computer?
Happy New Year and thanks again

Not really, but it would make it easier to keep a good backup.

OK, thanks so much. I'll pick one up on payday and transfer everything to it