I currently have a nice quiet PC that's starting to be a little slow. In the next few months, I'd like to upgrade it, also making it capable of software-decoding of HD content (HD-DVD and Blu-Ray as well as downloads). Ultimately, I may wish to take all of those components and bung them in one of those fancy HTPC cases in an AV rack, so I'd like to keep that in mind in terms of any upgrade I do now. My main confusion is... - what kind of motherboard can fit in my existing case (and a future HTPC case if that's not too limiting) - is this determined by 'socket' or 'form factor' (are they all currently ATX)? - what kind of RAM will go in that motherboard - DDR? DDR2? - and how much do I need? - what kind of processor should I be looking at to handle that content? Ideally I'd like to buy at that 'sweet spot' between price and performance that tends to exist, presuming that's powerful enough. I understand that the processor and motherboard are possibly a chicken and egg situation - what I choose in one area limits me in the other - so I'd really like it if someone could simplify that situation (and if my current or future case are limiting me there), as well as the issue of whether RAM needs to be installed in pairs or whatnot... My current setup is: Motherboard: Asus A7N8X Processor: AMD Athlon XP 2400+ 2.00Ghz RAM: 2x 512Mb DDR DIMM PSU: Hyper Type-R Modular 580W IDE HDs: 40GB System Drive, 80Gb Archive Drive SATA HDs: 2x Maxtor DiamondMax 10s - 1x 300Gb / 1x 200Gb (SATA-150, 7200 RPM, 8MB Cache) Graphics Card: NVidia GeForce 6600 GT (AGP) Sound: SB Live! 24-bit Optical: 2x IDE DVD Writers - which I'd like to keep and then replace with HD/BD drives when the time comes. I'm presuming the mobo, ram and CPU have to go and it's mainly the case/mobo/cpu/RAM bit that's a concern right now, but here are a few other considerations... Ideally I'd like to keep the graphics card for now (it's nice and silent, has DVI for the monitor and VGA for the projector, and I don't need any more horsepower for games) but I'd want to be able to upgrade it eventually to support HDMI and HDCP (if that's necessary). My sound card is also fine for the moment - I have a 5.1 amp that I probably can't afford to upgrade - although I've no problems with having that on-board as long as there's a digital output. The SATA HDs are controlled by an additional PCI controller card which I'd like to get rid of - my case can take 4 HDs and I'd like the motherboard to take 4 SATA HDs, with my current 200Gb one as the system drive and one or two new 500Gb ones for mass data storage. I quite like the idea of the 200Gb one being mirrored (RAID?) for backup purposes, but would that require another identical 200Gb drive, or could I use the 300Gb one to do that? And I'm guessing my Zalman flower CPU cooler has to go? Cripes. This is so wasteful! In fact, I'll pretty much be a case away from a whole spare computer! Whew! Far more than I intended to write, but if anyone could point me in the right direction, it'd be much appreciated.