Linux operating systems such as Ubuntu (even the many flavors of that one named version) work fine. It's just an operating system.
What matters to you, the use, is what you utilize on the current system and if you can do the same thing on the new system. If you utilize any specialized software - without some extra knowledge - you are unlikely to be utilizing it if you switch operating
systems. Now as for what "specialized software" is - that depends on you.
If you have to use Microsoft Office, for example - you may have alternative that will work for what you need... or those alternatives may cause you grief.
If you have to use Intuit Quicken or QuickBooks, for example - you may have alternative that will work for what you need... or those alternatives may cause you grief.
If you have to use Adobe Acrobat Professional, for example - you may have alternative that will work for what you need... or those alternatives may cause you grief.
The list could go on.
If all you do is use whatever web browser is put in front of you to surf the Internet and either use whatever email client/program/application that is put in front of you OR use the web browser previously mentioned to check your email (send/receive) - then
you could probably get away with Linux or even some tablet device based off Android or iOS even. If that is *all you do*.
There's also driver issues to be concerned with - particularly if you have external peripherals - like printers, scanners, cameras, etc. A lot of hardware still does not come with readily available drivers and even if they do - if you have never installed
drivers and the likes - you may have trouble there.
While Linux, in its many many many distributions, has come a long way in general population usability and maintenance - the latter can be an issue for those who have always just depended on their computer to automatically keep everything up to date for them.
;-)
But if you think you are up for the task - choose a distribution (and probably a sub-distribution) and go for it... Here's a partial list:
http://en.wikipedia.org/wiki/List_of_Linux_distributions
A lot of people have recommended (no ORDER...) CrunchBang, Bodhi, Peppermint or Lubuntu. Others have recommended
Zorin. There are dozens of others, but those keep getting repeated amongst the non-Linux die-hards - probably because of their closer look to XP than some others in some cases and because some of them
have been targeted towards the less command-line oriented Linux crowd for years.