If you are referring to the ubuntu releases you are running a very old release 9.04 that is no longer supported. As you can see from the first link support stopped Oct 2010.
If you want to use the newest stable release of ubuntu you have 2 choices:
1. a fresh install of ubuntu 12.10 (13.04 has just been released but might still be buggy).
2. do a step by step upgrade 9.04 -> 9.10 -> 10.04 LTS -> 12.04 LTS -> 12.10, which will take much longer and has a chance of failing leaving you with a broken system. Always wise to do a backup before attempting an upgrade.
You hardware would not have any problem with any version of ubuntu. 2.0 GB ram is more than enough and you have plenty of Disk space.
Your problem would be the many hundreds of MBs that you would have to download to perform all 4 upgrades and the amount of time to let the install take place. Then hopefully the upgrade would be accomplished without any serious problems which could happen because the older releases are not supported and some software has been removed from ubuntu.
It would be easier to do a new install side by side with your old version and then copy anything from your /home directory to the new /home. All of your personal files and additions (except ubuntu software) is located in /home. You would have to reinstall any ubuntu software and then when all is to your liking you can delete the old ubuntu.
Another factor is that the look and feel of gnome has changed a great deal since 2010 and many people do not like it. You can use the live cd to take a look and the new version to see if you want to use it before you install it.
You can email me for followup.