A somewhat high probability:
http://ark.intel.com/compare/37005,42925
What you need to do is run a diag program like speccy or Everest and get the exact chipset (945GL, 945GM, etc), then look up that chipset on
http://ark.intel.com and look at compatible products.
I think the only thing that will prevent the upgrade is:
A. BIOS limitations
B. the 9800 is 1066MHz FSB and your 4500 is an 800MHz FSB.
Get the exact chipset and post a pic it if you get lost comparing CPUs and chipsets on ark, I've done lots of CPU upgrades in laptops, more than happy to help.