Thanks
Now I know what you have, and it will help to give you good recommendations.
Because you have deleted some apps - and it will be difficult to say what ELSE is missing that simply copying apps back to your system might not be worth doing. I think you should reinstall the system, which would get all your Apple software back in place.
Did you get any disks with your Mac? particularly system disks - the original disks are a set of two grey DVDs, that would have system labels, such as "MacOS X" and the version number for the system, which would likely be 10.4.8
Because you have a newer system, those original disks may be a challenge to get everything working again, without erasing everything.
Another, better option is to purchase a system upgrade. You can get a newer system (MacOS X 10.6.3) direct from Apple for only $20
http://store.apple.com/us/product/MC573Z/A/mac-os-x-106-snow-leopard
Installing that would get most of what you deleted (and newer versions, too), and give you the big advantage of software that is more useable than the 10.5.8 system that you (mostly) have now.
The only thing that you haven't said is how much RAM memory is installed - which is on that same About this Mac window. 10.6 (Snow Leopard) requires minimum of 1 GB, and you may already have more.