If you efile your tax return without digital signatures, then you have to post/mail efiling acknowledgment (ITR-V) at the CPC, Bangalore. If you efile your IT return along with your digital signature, then you do not need to deposit
@ abhi: Saving digital signature in CD, email and other media excpet usb token is not a valid practice. For security purpose many companies and CA only prefers USB token to save there digital signature. You might be unawer about consequence of leaking your digital signature.