I suggest you defer on the graphics card initially. The integrated graphics is fine for normal work.
The 6450 is better, but does not qualify as a gaming graphics card, and you may have to abandon it in favor of something stronger. For gaming, you are generally looking at a $100+ graphics card. Some apps can use the CUDA capabilities of a Nvidia based card, so check that out too.
For windows, you also have the choice of a OEM license. It will be about $100. The main negative is that it is not considered retail, and the installation is tied to your current pc and motherboard.
A retail license can be freely transferred to another PC.
Upgrade is considered as retail. It will also cost about $100.
Have you ever owned a old copy of windows? If so, I think you qualify to use a windows upgrade package.
It need not be currently installed on the pc. In fact it is not possible to have it installed if you are converting from 32 bit to 64 bit. To do a clean install of a upgrade dvd to a pc without a suitable os, you first install, and do not activate.
That gives you a 30 day period of a functioning os. Then, you do the upgrade and activate.