hi Wort
Stepping up to an ssd is a good idea , it will dramatically improve your windows loading and application execution speed .
If you have not had an ssd before you will be impressed by the improvement.
I would as a precaution at some stage , especially if you only have the one HDD , get another internal or external drive for the purposes of backing up your data, there is no guarantee as to how long your existing hard drive will go for but like all mechanical HDD's at some point in the future it will die, so best to backup any important data in case of this eventuality .
For your 50€ i would add an extra £5.89 recommend this ...