Computers are dirt-cheap nowadays... I've built machines for 300-400 bucks whose level of performance was undreamed for 3 years ago (well, except maybe for video)..
The CPU upgrade here is not that obvious... Let's see.. He has a P2.4? Check.. Those were mostly made in 2003, were socket 423, and ran on 533 MHz FSB.. Unless he does have one of northwoods (s478), which opens him up for some old school prescott goodiness. Either way, there is not much in terms of updates given the mobo he has. For s423, his best bet is a P4B @ 2.6 Ghz, which is hardly an upgradel; for s478, he can get a 3.2 prescott or northwood which will yield a slight boost, but it won't be dramatic... Any faster CPU, and you need a new mobo... And then you realize that unless you ebay or settle for a crash ASRock hybrid board (which are, nevertheless, good value for money), you'll need to upgrade your RAM.. which is not a problem, considering 30 bucks yield you 2 gigs of ddr2 if you know where and how to buy your RAM. At that point, we changed the CPU, the Mobo, and the RAM.. Will definitelly cost more than 50 bucks, but on the other hand, for about 150 you could be having something amongst the lines of X2 3800... Which should be more than enough to decode anything HD (except for extremely high-bit-rated content)...
And that brings me back to that Radeon 2400 card... If you can find it in AGP trim, it's your cheapest way into the world of HD...
