After VMware announced that general support for ESX 3 was about to expire I received several emails with the same question. What’s the difference between general support and extended support? I think the following picture clearly depicts what the difference is between general support and extended support:
As you can see the only difference is that “non-critical bugs” will not be fixed and there will be no support for new hardware. Extended support ends on 2013/05/21 for ESX 3.5.
You can find all info regarding the VMware support policies here. Keep in mind that with vSphere the policy changed! There is no such a thing as “extended support”. General support is 5 years with vSphere and after that it is Technical Guidance only.
Also with extended support you will not be able to download these versions. as they will be “End of Availability” also
http://www.vmware.com/support/policies/lifecycle/vi/faq.html
so download what you need now and dont lose it.