I have not updated my MacBook for quite a while and still run Mac OS X 10.4.11 (8S2167) on it.

Two questions you have to ask. 1) Can your computer run a newer system? 2) Do you want to upgrade to a newer system?

To answer the first, get more information about your computer. Go to the Apple in the upper left corner of any window, then "About This Mac", then "More Info..." Copy and paste the information here, but omit the serial number and Hardware UUID (if present). Compare the information with the requirements for different system versions. If it's a matter of too little RAM ("memory") you can probably buy more. If the processor is wrong then you have to buy a new computer (or stick with a lower version).

Snow Leopard 10.6 Technical Requirements - http://support.apple.com/kb/SP575 - note by K Shaffer - http://discussions.apple.com/thread/2718050?answerId=12921514022#12921514022 : "Some early Intel-based Macs can't use Snow Leopard 10.6 installers; of those, the Core Duo (not 2 duo) were suspect and had issues." - and a qualifier by "a brody" http://discussions.apple.com/thread/2741900?answerId=13028822022#13028822022 : "I think that refers to the ones without at least 1 GB of RAM."

Snow Leopard 10.6 Technical Requirements - http://support.apple.com/kb/SP575 - note by K Shaffer - http://discussions.apple.com/thread/2718050?answerId=12921514022#12921514022 : "Some early Intel-based Macs can't use Snow Leopard 10.6 installers; of those, the Core Duo (not 2 duo) were suspect and had issues." - and a qualifier by "a brody" http://discussions.apple.com/thread/2741900?answerId=13028822022#13028822022 : "I think that refers to the ones without at least 1 GB of RAM."

Macs and Software that will run with Snow Leopard (Mac OS X 10.6.x) - https://discussions.apple.com/docs/DOC-2455

Mac OS X: System requirements for Lion - http://www.apple.com/macosx/specs.html

Question #2 has to be decided by you. Newer systems may run slower on an older computer. Some older software may not run on newer systems and while upgrading OS may be cheap, buying all new software may not be so cheap. Upgrading may require hardware upgrades and do you want to invest that too?

A Mac OS X 10.6 Snow Leopard Application Compatibility List - http://snowleopard.wikidot.com/

Lion application compatibility - http://www.everymac.com/mac-answers/os-x-lion-faq/os-x-lion-compatible-incompati ble-applications-quicken-office-eudora.html

Lion application compatibility (2) - http://www.everymac.com/mac-answers/os-x-lion-faq/how-to-check-powerpc-applicati ons-not-compatible-with-os-x-lion.html

As a general tip I would say if you're running Tiger on a machine now, you may not want to go all the way to Lion (even if you can). It may demand more resources than your computer is comfortable in running. You may find a lot of applications no longer work or are really slow. Upgrading two system versions (10.4 --> 10.6) is reasonable. Upgrading 3 versions may be possible but is like trying to drive a 30 year old car at 80 miles per hour non-stop. If I had your computer I would take it to Snow Leopard and stick with that for another year or two before updating your whole setup.