The ASRock board are OK, you might end up with a bad power supply, being only $15.... The only thing is see bad about the specs is that it is only DDR400, right now the DDR2 667 sticks are going for very cheap, right now 1 GB sticks are around $50 or so, depending on who you're getting it from, whereas the DDR 400 are about double. As far as hard drives, that's fine, however seagate's have a 5 year warranty, however, the store you're getting this from seems to be selling off the warranties...
---if you do decide to go with DDR2 memory you'll need a board that will support DDR2. Soon enough DDR memory will be hard to find so if you plan on upgrading memory you might want to go ahead and get DDR2 instead.