In 5 years they will probably have 100TB+ drives and CPUs with 8 cores and 32+ GB of RAM and will cost only $750 for a complete system with a 32" LCD monitor. Such is the state of computer technology. The best you can buy today is worth a tenth or less of it's value in 3-5 years. You just have to buy what you can afford that meets your needs today and the not so distant future.
I should add that you would probably want to get a DVD tower with 4 or more drives in it to import your data. That will drastically cut your time down.
You may also want to consider archiving, selling or giving away some of your older, not watched titles (or start up a rental company). It's good to
5S every now and again. You have some movies that you don't like, are poorly rated, have duplicates of (ie: reg edition + platinum ed + ultra deluxe collectors ed box set, etc).