yes buddy you can make your PC boot automatically provided power supply to it...
just goto the Bios (F2 or del or some other key) at the very first screen when you switch on the PC there you can search (depends on the make of board,the options are placed ) check there will be space for entering the time for the pc to boot set it and it will switch on automatically
about the TATA dialer yes that also can be done simplest method is just create a shortcut of the dialer and drag that to start menu, programs, startup .. so when the PC boots the dialer also dials the connection