If I were her, I'd look at an Apple refurbished unit - full one year warranty, fully factory refurbished to like new condition.
The caveats to look for would be at least 4GB memory (2GB is still often used as a min. required, but its barely minimum for many uses, even with older versions of OS X). A refurb i5 intel mini with 4GB RAM is only $509.00 USD and an 8GB version only $589.00 USD.
P.S. If she is writing a novel, please, please insist she also invest in a dedicated backup solution, and ideally two so she has redundancy (e.g. a Time Machine volume for individual file recovery, and maybe a portable external drive for a periodic whole system clone). Whether buying a new machine, a refurb or used, bad things can happen to good hardware at any time.
Hi Michael, thanks for those thoughts. We were't really looking to spend that much, so I'm not sure a refurb is the right option. I did think that a good idea might be to get an older Mac Mini and fit in a new, low-capacity solid-state drive (just enough for rtf files). We could back up to a separate USB drive, and print out as we go along.
My theory was that if the computer wasn't connected to the internet, we'd at least be safe from viruses, having to update (to more demanding software) etc.
Does that seem sensible, or is indeed foolish to think one can buy an older Mac mini for word processing, and still be relatively safe?
My issue with used would be it often is contrary to your original post item 2).
If reliability is of utmost concern, then new or refurb with a warranty would be my choice. Used is usually a crapshoot as far as the state or condition of the hardware. And you have no recourse if it does fail, other than paying to fix it or replace entirely yourself.
And seriously, new, refurb or used - there is no such thing as a 100% guaranteed electronic device, so a backup is essential, not optional, if you value the data on that machine.
For basic or even complex large file word processing, I would not bother with an SSD drive at all. Not worth the expense to my mind, as the hard drive is not going to be the bottleneck at all (unless you get something with bare minimum RAM and are seeing a lot of pageouts ot swap). Get something with 8GB of RAM and even a massive and complex MS Word document is going to be easy to work on as disk I/O is minimal and the entire file will be in RAM when in use anyway.
We'll definitely backup - at least to a USB drive and hard (print) copy.
I thought of an SSD drive only because they are supposed to be more reliable, and because the computer would start up quicker.
It seems to me that a warranty is not as much use as it might sound - after all if it's new or just had a refurb it's unlikely to fail within a year. My main criterion, which I should have mentioned before, is to keep th cost down - we're on a tight budget.
Perhaps it would be best to go for something that isn't Apple at all - I thought Apple in the first instance because of reliability: I've had my MacBook for 7 years and no problems.
Adding an aftermarket SSD drive won't help keep the cost down though. To some extent, often startup doesn't matter much as many people never shut their Macs down. My MBP has not been turned off for more than a few days in 4 years - I'll sleep it when away from it, and the hard drive and screen are timed out to sleep, but I don't bother shutting it down and rebooting it often. And the difference in boot time for an SSD versus a HDD is likely going to be under one minute on any machine made in the last 3-5 years, so is it worth the cost for that, especially if you are only rarely restarting the machine? To my mind that answer is no, but everybody is different.
If I/O is an actually bottleneck or high activity issue on a machine, that is when an SSD becomes worth the extra cost, to my mind. For word processing, I/O will not be a limitation at all, even with an older 5400rpm conventional HDD, so using an SSD is largely paying for something without any real benefit. Even in terms of reliability, SSDs are hardly error free or not prone to failure, and in real world use or MTBF type ratings, a good quality conventional HDD is just as reliable as any decent SSD (and sometimes is more so for certain types of failures under heavy use read/write conditions).
Buying used is fine, if you know the place you are buying from and can trust them to only offer decent items. As long as you backup regularly so you can recover, a used item may suit your budget and needs just fine.
In the tight budget scenario though, it is hard to beat some of the available Windows PC consumer machines, and many of those are pretty good quality. MS Word is MS Word by and large, whether on OS X or Windows. Keep in mind for the PC route, the cost of decent AV (although many of the free tools are very good and more than enough if you are educated and savvy about what to do and not do with email or web sites&links).
2. It must be secure, i.e. not liable to break/malfunction easily. (My partner is writing a novel, so she doesn't want to lose it half way through!)
Regardless of computer, solution to this is backup, backup, backup.
Never, ever trust critical work to a single copy. With anything critical,
multiple local copies on multiple devices is not desired, but a requirement.
You must also have offsite backups as well.
Relying on a single copy of critical work is an accident waiting to happen!