Good advice from others here. If it were my system, I'd purchase an external HDD since it can be used for many purposes, storing images, unattended incremental backups, etc.
Once you get your Laptop running with a clean install, I'd run a full-HDD Image so that you'll have a complete HDD backup ready for future rescue use.
My other advice would probably be seen as "overkill" by some, but I'd purchase a spare HDD for your Laptop.
Conventional ("spinner") HDD's have become inexpensive lately and there are several reasons that it's a good investment (my opinion):
- You'll have a spare HDD ready if your original HDD fails or gets compromised by malicious content
- You can use the spare HDD to maintain a periodic cloned copy of your existing HDD. This will provide a fast plug-play replacement for your entire HDD in the event of the above-mentioned events. It's also a good backup for human error, ie, download gone bad, or a mistake in the Registry editor, among other possibilities.
- It provides a fast recovery method from virtually all malicious infections. As hamluis mentioned, sometimes the best way to recover from some malicious infections is to wipe the HDD. If that's necessary, then the user has to re-install the OS, reload all programs, restore your user-specific folders, items from backups.
If you're maintaining a periodic clone backup or full-HDD imaging plan, you'll avoid the time-consuming task of re-installing everything on the new HDD.