I've had windows 7 64bit for a couple of months now and I have to say it has probably been the most hassle free windows installation I've had (hope that doesn't change!). Just does what it needs to do, and fast. Use a variety of apps on it, from 3ds max, photoshop, udk to adobe premiere and also play games on it (latest…
If you have the option, go for 2 HDDs, one smaller capacity for your OS, one larger one for storage. If not, go for the 1TB, unless HP are charging something silly for it. 1TB is quickly becoming less of a shockingly large amount of space and it's probably safer to grab the extra now rather than wait until you fill the 640…