One more "YES" for upgrading it.
My advice:
Get a 2.5" SATA SSD. It doesn't have to be "the fastest". I suggest you "buy for price", I like Crucial and Sandisk.
Get
ONE 8gb DIMM module, and replace the "topmost" 2gb DIMM while you have the back off to replace the HDD.
This will give you 10gb of installed RAM, as much as you'll ever need.
Also:
BE SURE TO USE THE RIGHT TOOLS for the job.
Phillips #00 driver
TORX T-6
Go to ifixit.com to see the replacement guide.
This is an easy job, and ANYONE can do it in about 20 minutes. The hardest part is removing the screws holding the back plate on, and replacing them later on.
You didn't tell us how large the original hard drive is.
I'd get an SSD the same size or larger.
Then, you can just "clone over" the contents of the old drive to the new SSD.
I'd suggest either CarbonCopyCloner or SuperDuper for the cloning.
Both are FREE to download and use for 30 days.
This will
cost you nothing.
One more thing:
I suggest you buy one of these:
SABRENT 2.5 Inch SATA to USB 3.0 Tool Free External Hard Drive Enclosure [Optimized for SSD, Support UASP SATA III] Black (EC-UASP)
tinyurl.com
Put the SSD into it FIRST, and connect it to the Mac.
Use disk utility to erase/format the SSD.
Then use CCC or SD to "clone over" the internal drive
BEFORE YOU OPEN UP THE MACBOOK.
This way... if something doesn't go right...
YOU STILL HAVE A WORKING MACBOOK.
Once you do the clone, now you can boot with the option key to invoke the startup manager, and boot from the SSD while it's still in the external enclosure.
This way, you can test it to be sure it works.
If it's "a good boot", NOW is the time to shut down, open the MacBook, do the drive/RAM swap, and close back up.
Then, set the Startup Disk to the new SSD, and you should be done.
Put the OLD drive into the enclosure.
It can still serve as your backup drive, or extra storage.