Hi Loga,
If i purchase the voucher for the present SCWCD exam and incase i decide to take it later in March/April when the new exam is available, will i be able to use the same old voucher for taking the new exam instead?
YES. As your voucher does not contain any exam ID, you can use it to register any 310 prefix exams (this info should also be available in your voucher).
For the current exam, apart from Deshmukh's book what other material would you recommend as a must read?
I think Deshmukh's book is enough, I only used that book to prepare my SCWCD, together with the software JWebPlus.
If you want more practice, you may also try the mock at
www.j2eecertificate.com Nick.
SCJP 1.2, OCP 9i DBA, SCWCD 1.3, SCJP 1.4 (SAI), SCJD 1.4, SCWCD 1.4 (Beta), ICED (IBM 287, IBM 484, IBM 486), SCMAD 1.0 (Beta), SCBCD 1.3, ICSD (IBM 288), ICDBA (IBM 700, IBM 701), SCDJWS, ICSD (IBM 348), OCP 10g DBA (Beta), SCJP 5.0 (Beta), SCJA 1.0 (Beta), MCP(70-270), SCBCD 5.0 (Beta), SCJP 6.0, SCEA for JEE5 (in progress)