In my fathers work they disposed all the old PCs and between all that ancient junk there was one which was actually decent for browsing at least. It didnt booted up and while Im not a huge expert I noticed that those fools there didnt noticed that only the case/motherboard jumper cables where disconnected, so now it runs.

mobo: Gigabyte GA-G41MT-S2 (switched the CMOS battery cause PC was not on power for 4-5 years)
CPU: Celeron E3400 2,6Ghz - bought a Core Duo 2 E8500 3,16 for 4€ second hand
RAM: 2GB DDR 1333 - I switched out for Kingston 2x 4GB 1333 dual channel from my previous PC
graphics: Intel GMA X4500 integrated
HDD: WD 500GB
drive: non-working Samsung SH-223 (something is rattling inside) - I got from my father friend a Hitachi DVD-RW, ancient but works.
Eurocase 400W PSU
Bought a Comfast wireless adapter (Realtek 8188) to connect to net trough my router.
The HDD had a non-activated Win 7 32bit on. I feared its some not legal copy but it activated without a issue on page of MS.

Now the 2 problems:
1. The Windows is legal but it had no sticker or media. I used Magical Jelly Bean Keyfinder to dig out the key - can I be at peace that this is the proper one?

2. Being 32bit will not use the 8GB RAM, can I make a clean 64bit installation with the same key?

Also if someone has a cheap tip to upgrade, pour it out, but it will only a browsing PC for my near 60 year old parents.