First Build: What mobo should I buy?

This is my first PC build ever, and I've decided to make it more of a challenge. I've got an old LPX style computer (Low profile desktop) with a wimpy Pentium w/ MMX running at 200Mhz. I'm going to scrap the old LPX MoBo, sell off the processor, and basically just keep the case.

My idea is to make a basic DVR/Multi-Format DVD Recorder (with a TV tuner of course). The question is, what would be my best choice for a mainboard? I want high speed data transfer to DVD and Hard Drive, so I intend on using SATA or SATAII. I'm also on a small budget of around $400. Any thoughts?

Are you wanting to go 32 or 64 bit? Probably 32 if your on a budget, and if your wanting high speed data transfers you might want to think about getting something that has RAID and you can spend the rest of your money on ram and a good video. You might want to think about getting a new case, the low end ones arent that expensive. You can get either a mobile 2600 AMD or a regular barton core. All of these are pretty fairly priced. A SATA raid is what Ive been running on an Abit NF7-s like so many of us have been running. Goood board and good price. You didnt mention whether you wanted to overclock so Im going to assume youre not.

I don't think it makes sense to build a brand new Socket A system right now. It's not only a matter of 32-bit vs. 64-bit, but Athlon 64 systems offer significantly better performance than Athlon XP systems, even when running 32-bit applications. You can get a decent socket 939 motherboard and A64 3000+ CPU for less than $250, which is not a whole lot more than you'd pay for a socket A setup.

Your choice of motherboard really depends on how you plan to use the system. I know you mentioned using the system as a sort of media center, but do you plan to do any gaming? How about overclocking? Do you have an AGP card that you want to use in your new system, or will you be buying a new video card? The answers to these questions are important when selecting a motherboard to build around.

Well I've only got a PCI GeForce card that is currently in use in an eMachine. I don't plan to do any gaming with this PC. I plan to use it strictly as a DVR and DVD recorder with a few other minor capabilities such as MP3 playing and importing/exporting video and picture files. I do plan on overclocking, but seeing as I am trying to use a low profile case, I don't think I'll be able to cool it by any other means other than air. I had planned on making this a 64 bit system, seeing as 32 bit will more than likely be replaced completely within 5 years or so.

The reason I am considering the use of an LPX case is the fact that (A) I've got one readily available and (B) I'd like it to be similar to the same layout a DVD/VCR would have (flat, but larger than a regular vcr or dvd player)
If there are any other case suggestions that would mimic a DVR box without much cost, I'm open.