Reasonable PC Specs

If this isn't a gaming machine then i'd suggest keeping thing basic and allowing room for expansion later.

nVidia seem to have a lot of different style drivers at the moment. Both the proprietary driver and the new properly open source "Noveau" one are both much much better than the ati ones so i would suggest an nVidia card. Sadly it seems that ati are the "good guys" so i'm kinda suggesting the unpopular 'opposition' however it seems that nVidia have put a lot of work and resources where ati have just given promises and information. I have an atic card before anyone gets huffy about this answer. Intel graphics seem really poor by comparison with either.

I would keep the sound on-board and look around for a soundcard sometime in the distant future to 'upgrade' the machine a little later ;) Motherbord sound is usually far better than i need anyway.

2Gb Ram is plenty unless you do seriously heavy gaming in emulators on multiple monitors. On an over-clocked to 2.8GHz cpu (on a special but old collectors mbord) i sometimes manage to push it up to 1.5Gb Ram used when i'm watching HDTV and doing tons of stuff. Restricting yourself to 2Gb means you're well within the 4Gb limit for Ubuntu Desktop Edition 32bit and 2Gb also means you don't even need the special tweak to do that. Desktop Edition 32 bit has the best and easiest repos and links well with Wine which is also primarily 32bit. It has slightly lower overheads on ram usage as it tends to write full blocks of 32bits rather than half-empty blocks of 64bit stuff into ram/swap. 64bit cpu and dual/quad core is definitely worth going for and the 32bit version of Ubuntu works really well on this type of setup. Getting 1 or 2 large sticks of ram minimises the slots used up which makes it easier to buy additional sticks in a year or 2's time ;)

I always get edgy about the Usb ports at the front of the machine. I think they tend to look untidy when being used (although they are very handy). Also i worry about the "sheering factor", ie what if i accidentally knock the usb stick with my elbow (or foot depending on where the machine is), possibly permanently damaging my main machine? So i tend to plug a cheap but nice looking usb 'hub' into a usb port at the back of the machine via an extension cable. i've even stood on the hub a few times without damaging my main machine ;) (my hub survived to, amazingly).

Make sure you follow instructions about reducing static on your hands and fingers especially when dealing with the mbord and ram but also the graphics card tends to be a bit vulnerable to even quite small static charges. It's worth continually keeping touching the machine's metal case to keep discharging any static build ups which are likely to occur from touching anything especially plastic and perhaps hair or the power supply. Which reminds me. It's worth getting a decent power-supply because this isn't something you want to have to re-buy again later after you've added loads of hardware (dvd players etc) over the next few years.

I tend to use the old cd player from my old machine most of the time but sometimes am forced into using the new dvd player but i try to reduce wear&tear on newer bits of kit by using older stuff where possible.

Good luck and do check up on the "Supported Architectures" page in community documentation and/or elsewhere, also make sure you are going to be able to test pats out quickly enough & that you can return stuff and get money back on anything that doesn't work well in linux. Stating that as a reason for returning an item would be good to force hardware manufacturers to realise they have to take more notice of us than they currently try to get away with.
Regards from
Tom :)