Oh my, I hope for the best for your therapy.
Can I know more about your old pc? especially its RAM(how big and how many sticks are there), psu (what brand and how many Watt), and motherboard (brand and type).
Your old cpu has 4 core/thread. It should be suffice in term of cpu power. If you really want a real upgrade, an SSD will boost up your total performance. GPU will help but since you only playing bejeweld and solitaire, there should not be the issue.
For me SSD is a must. Ever since cpu has 4 core, the HDD has been the one that dragged all pc performance until SSD came to economical value. My old amd phenom II X4-B55 (4 core also) was boost with an SSD and still using it now for my office use. If you are using window 7 or above, using SSD will make the start up under 10 seconds (counted after bios load finish).
Since you are using only those game, a 120Gb or 240Gb SSD should be enough.
$45 Sandisk SSD PLUS 120GB 2.5" Solid State Drive
https://pcpartpicker.com/product/m34NnQ/sandisk-ssd-plus-120gb-25-solid-state-drive-sdssda-120g-g26
$76 ADATA Ultimate SU800 256GB 2.5" Solid State Drive
https://pcpartpicker.com/product/7YQRsY/a-data-ultimate-su800-256gb-25-solid-state-drive-asu800ss-256gt-c
You will have to reinstall the window onto the SSD tough.
Further optimization will require the information I have asked above.