MacBook Pro SSD and RAM upgrade
Upgraded my MacBook Pro to SSD and to 8GB RAM. Wasn't very difficult, but it took some time as I needed to reinstall OS X Snow Leopard and then upgrade to Yosemite.
The SSD makes a big difference. Feels twice as quick when booting up or loading apps.
Bought my memory from crucial.com for under £100.
Here is an instruction video on how to do the upgrade.