Hi there,
Ortopi. There are no dumb questions to any legit queries..
If you mean upgrading HDD as to storage capacity,
just buy another 750 GB HDD and place it in the other drive bay (the G74 has 2 drive bays).
It would be wise to buy a new one with the same brand similar to what you already have,
assuming that it's working well.
But if you mean upgrading HDD as to performance and speed, I would recommend
buying an SSD instead as your OS drive, then either do a fresh install of the OS
or clone the OS from the existing HDD to the SSD. You can then format the HDD
and make it as your secondary drive.
As to RAM, an 8 GB capacity would handle most computer usage.
However, some would have 12 or 16 or 24 or even 32 GB RAM (I have 16 GB RAM).
Thing is, there's no really big jump as to performance, in any of these configurations, IMO.
And again, buy additional RAM that has the same model as what you already have.
Or at least ones with the same specifications (I have 12 GB ASint and 4 GB Kingston).