I think it's far cheaper to get a 300 gigs or even a 400 gigs HD than 2 x 160, actually i read seagate has launched it's newest HD with 500 gigs capacity. And from what i read, seems u like to try new things, so a big HD will be nice, as long as it fits ur budget. And from my personal experience, Seagate will be nice, and i heard they guarantee their HD for 5 years, instead of 1 year with the other brands.
About M/B, i think it's relatively the same with all the major brands: Asus, MSI, Gigabyte, ABIT, etc. If u're lucky, u'll get one which will work perfectly for years to come, but if u're not, u'll get one which will make ur days in hell. If u really want a good one, try some brands focusing in server M/B, like Tyan, because they tend to be more problem free and more stable. And be sure to look for a M/B with all the features u would like, for example extra slots for extra HD, one of my friend just realized that he needs more slots for HD, even though he already got 4 SATA + 1 IDE HD (900+ gigs).
For graphic cards, the best ones i know are nvidia 6800 or radeon X850, but they will cost an arm and a leg, so i won't recommend them. A 6600 or X800 will suffice for any games for years to come.
As for RAM, 1 gigs of RAM should be enough for any personal use i guess, and u can always add another if u want to in the future, just be sure to get a M/B with at least 4 slots for RAM, and the Corsair value select is a good (and cheap) choice.
For processors, u can buy anything u like, but i think a64 3500+ is more than enough for years to come, and a64 3800+ doesn't offer much more power, but costs a whole lot more.
U will need a good casing and PSU, nowadays computers needs more and more power, i even heard that P4 4GHz was canceled because it consumed too much power and the heat generated was too much. A Thermaltake casing and PSU should be enough, just be sure to get at least 400W PSU
For the optical drive, i agree that a DVD writer is very cheap nowadays and u can read and write CDs with it too. For the brands, i personally like the cheap and reliable Liteon, it's one of the cheapest so if something goes wrong, u won't cry too hard while dumping it into the trash can and buy a new one.
Apart from the CPU itself, i think it's much better (and much more comfortable) to buy a not too high spec CPU and invest the rest of ur money in a big, nice LCD monitor, a UPS, a nice wireless keyboard and mouse (Logitech MX 1000 is quite nice), an all in one printer, scanner, and copier, and a good set of speakers.
Keep in mind that u also have to spend some money to buy the softwares, and they can be very expensive.
Good luck with ur computer
