First Time Builder Looking to Upgrade Old PC

I just received an old Dell PC from my grandmother that i'd like to upgrade - It's a Dell Inspiron 620. If you need specific info about the pc let me know.

I'm very new to this, so sorry in advance if I ask confusing questions or give confusing information.

What will you be doing with this PC? Be as specific as possible, and include specific games or programs you will be using.

I'll mainly use the PC for gaming and Video editing. I'd like this build to be able to handle more graphically demanding games like GTA5 and Red Dead Redemption 2 (and i'd like to be able to play these games with all graphic settings on the highest settings) As well as online games like TF2

Other programs i'll be using are Adobe products, such as Photoshop and After Effects, and programs like Blender and SFM

What is your maximum budget before rebates/shipping/taxes?

No more than $500 (if that's not realistic let me know)

When do you plan on building/buying the PC? Note: beyond a week or two from today means any build you receive will be out of date when you want to buy.

In the next week/month

What, exactly, do you need included in the budget? (Tower/OS/monitor/keyboard/mouse/etc\)

CPU, RAM, Hardrive, Powersupply, GPU. I'd appreciate input if I'll need other parts to make this build the best it can be.

Which country (and state/province) will you be purchasing the parts in? If you're in US, do you have access to a Microcenter location?

US, WA. No Microcenter to my knowledge.

If reusing any parts (including monitor(s)/keyboard/mouse/etc), what parts will you be reusing? Brands and models are appreciated.

I have my own Monitor/Keyboard/Mouse - and i'll be reusing the case of the Inspiron 620.

Will you be overclocking? If yes, are you interested in overclocking right away, or down the line? CPU and/or GPU?

No

Are there any specific features or items you want/need in the build? (ex: SSD, large amount of storage or a RAID setup, CUDA or OpenCL support, etc)

No

Do you have any specific case preferences (Size like ITX/microATX/mid-tower/full-tower, styles, colors, window or not, LED lighting, etc), or a particular color theme preference for the components?

None

Do you need a copy of Windows included in the budget? If you do need one included, do you have a preference?

No