Q: Just brought a older imac

did you get the system restore discs? if not be very nice to this lady until you get the password.

You can reset the password from a Mac OS X install disc.

http://support.apple.com/kb/HT1274

If you don't have an install disc you can always use this trick:

1. Boot into single user mode (press Command-S at power on)
2. Type fsck -fy
3. Type mount -uw /
4. Type launchctl load /System/Library/LaunchDaemons/com.apple.DirectoryServices.plist
5. Type dscl . -passwd /Users/username password, replacing username with the targeted user and password with the desired password.
6. Reboot.

http://hints.macworld.com/article.php?story=20080414140636495

says its running 10.3.9 G5

This is a fairly old release of Mac OS X.  I believe it was the last update of 10.3.  10.3 is panther.  I do not belive there is a current web browser for 10.3.  Try iCab.  icab.de  download file on any computer copy to g5.  double click to uncompress.

You should consider updating to Tiger 10.4 or leopard 10.5.

Mac OS X 10.4: System requirements

http://support.apple.com/kb/HT1514

Requirements for Mac OS X v10.5

http://support.apple.com/kb/HT3759