I had had a VMware VCP 4.1 ICM training in June 2011.
However dude to some reasons i did not write the certification.
So is that 4.1 training still valid ??
Will an upgrade class on VCP 5.1 allow me to write the VCP 5.1 certification?
Yes the training is still valid and you will be able to sit for the VCP4-DCV exam. The training remains valid as long VMware is offering the VCP4-DCV exam.
Whether you sit for the VCP4-DCV exam or not you will still need to take at least the VMware vSphere 5 What's New Class? before taking the VCP5-DCV Exam - you can learn more here - http://mylearn.vmware.com/mgrReg/plan.cfm?plan=12457&ui=www_cert
I have also moved your question to a more appropriate forum.
1. If you only want to achieve VCP4-DCV, pass the VCP410 exam.
2. If you're happy with just achieving VCP5-DCV, take the What's New class for vSphere 5 and pass the VCP510 exam.
3. If you'd like both VCP4-DCV and VCP5-DCV, do both of the above.