Whatever you buy, try and buy a tiny bit more than you currently need, as you will probably use the machine for at least 3 years. So add more memory (not necessarily from the manufacturer, where they overcharge for extra, but from places like Crucial.com...) and get the biggest hard drive you can afford. You will always expand your use to fit the size you have, between just collecting stuff and having every new rev of OS's and Apps need more space to run. A remember to "soup it up" in between the next purchase and now. It could last 6 years that way. I've done it for graphics, you definitely can for this kind of work (for a lot less $, too.)
The most cruel aspect? You did your database and the HD died. That stinks. Last Dec. I bought 2 new320 gig portable HD's to use for teaching. I transferred everything back onto my main computer, so that I could resort and send to the appropriate HD for my classes. I did this Dec. 23rd. December 24th I woke to to the spinning rainbow ball of death. I restarted, and it would not boot up. I went to Apple store that day-diagnosis? Dead HD. Unfortunately, as I transferred from the other small HD's, I deleted. So I lost 4 years + of teaching materials. Never again. Live and learn.
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“Lying in bed would be an altogether perfect and supreme experience if only one had a colored pencil long enough to draw on the ceiling."
~Gilbert K. Chesterton