Does windows 7 need a power cord for the computer and 1 for the cpu

Tally 7.2 is not longer supported. You might need to upgrade to the newest version.
The only other suggestion is to see if you can run in XP Mode. This will depend upon your computer requirements.

Running Windows XP Mode requires:

1. Windows 7 Professional, Enterprise, or Ultimate editions.
2. A computer capable of hardware virtualization. This means your computer has a central processing unit (CPU) with either Intel-VT or AMD-V virtualization features.
3. Virtualization features turned on in your computer's basic input/output system (BIOS).

To determine whether your computer's CPU is capable of hardware virtualization, go to the Windows XP Mode and Windows Virtual PC support website and download a utility that can check whether your Intel or AMD CPU is compatible.

http://www.microsoft.com/windows/virtual-pc/support/configure-bios.aspx

To find your brand of processor so you can download the appropriate utility, click the Start button , right-click Computer, and then click Properties. Under System, next to Processor, you can see what type of CPU you have.

Even if your CPU can run Windows XP Mode, you might also need to turn on virtualization settings in your computer's BIOS. Procedures vary depending on the BIOS manufacturer. For more information, see BIOS: frequently asked questions.

http://windows.microsoft.com/en-us/windows7/BIOS-frequently-asked-questions

For more information, please logon to:
http://windows.microsoft.com/en-us/windows7/install-and-use-windows-xp-mode-in-windows-7#section_3

Regards

Riztech