Fresh instal better or not needed? (used PowerBook purchase) Newbie

Hello,
This is my 1st post so be gentle please.
I have just bought a cheap PowerBook G4, 1 GHZ, 2GB RAM running OS X 10.5.8 and as Im a total newbie to Mac I wanted to ask some simple questions.

I want to wipe the drive and start fresh like I would normally do if I were buying a 2nd hand Windows PC.
With a Mac is this really necessary? Can I achieve the same results without wiping the drive?

As I have no idea about Macs I dont know if this machine needs to be wiped or not.

So my question is simple,
Should I just create a new admin account and remove the other accounts or reinstal the OS and start fresh.

cheers

It's really a preference thing, as I am sure the you will get in the many replies to come!
Whenever I install a new operating system to my macs, I like to do a clean install (starting fresh).
Then I know that there is no junk left behind to worry about which may effect performance, and this has always worked for me.
I read many posts from people having problems, and often think that I don't encounter this because I always do clean installs.
Once again, I believe that this is a matter of opinion.

Thanks for the speedy reply 6string,
Another problem I have is that the machine didn't come with an OS disc.
So for now I'm limited until I can purchase a new disc.
Is it possible to get a replacement disc from Apple for free?
(long shot kick de bucket question I know)

But you have answered my question, fresh instal looks better for me.

This laptop has a 60GB HD and its already used 45GB! surely this isnt all software the last user has added.
I wondering if the user has some files still on the machine that are hidden?

need a decent scanner to locate them all I think.

With 10.5, it takes up about 20GB, so there is definitely stuff from the previous user.
Long shot indeed, but if you do purchase leopard discs, make sure that it is the black ones with the X on the disks (retail version), and not the grey ones which are system specific.
What you can do, is use a programme like Carbon Copy Cloner to copy the disk image from your mac to an external drive.
Google or check out mac forums for the many techniques that people use.
Back up your system before trying anything, in case you run into trouble, and for that matter, you should always keep a current working backup on an external drive.

Apple will not supply free discs but you can certainly try them out. As suggested look for Leopard full retail install DVD. The install DVD is essential for doing things such as Repair HDD etc. so you do need it, the wipe the drive and do a clean install and update to OS X.5.8.