I have downloaded both demos of FIFA 2004 and PES 3. And can't stop playing them since then. Honestly, I think both are very good games, and it is a good news for consumers like us. Here is my opinion about 2 games(based on the demos):
Gameplay wise, PES series used to beat fifa series comfortably. But it isn't the case this time. In my opinion, PES overall is still slightly better thanks to the fluent and responsive control. I love the header and shooting system PES more than FIFA's one. The ball physics of shooting in PES is more real than fifa one (just look at the goals!). But does it mean PES gameplay beat FIFA's by every means? Certainly not for me, FIFA 2004 does have some innovative controls which PES is lacking. Being able to control the power and direction of through pass is one of those, being able to call player to run is another one which I think PES should have(or may be just because I don't find how to do it in PES, if so please tell me), for so many times in PES, i am so annoyed that my teammates controlled by computer just standing and doesn't run in free space (and this is one of the reason y i like cooperating with friends on PES more than playing on my own because they know how to run!). The free kick is also better in FIFA 2004 which allow u to control the curve and target. For corner kick, both FIFA and PES got their own advantage, i like FIFA one that player can push around when trying to get the ball which just look like the real thing we see on TV. But as I said, PES got better header system which is very important in attacking and defending corners, and PES also got more players in the box while FIFA just got 2 or 3 for each teams and in this case, PES is more real. Actually I somewhat prefer FIFA control ability to PES one, but FIFA control is not as responsive as PES, that's why I give PES a win this time. But EA is catching up quickly, FIFA 2004 control is already much more respontive than 2003 and earlier fifa series. So if EA finally gets a control which is as responsive as PES in FIFA 2005, PES will not be the king anymore!
SO how about difficulties? I have heard so many people saying FIFA is too easy and PES is much more challenging. But I am sad to tell PES fans that FIFA 2004 actually is more difficult to beat than PES. I play the demo of FIFA 2004 for around 10 hours now, and I still got beaten up 4-1 and 5-1 quite often and just managed to win the game once(for world class difficult of course). And I can tell computing doesn't cheat as much to make the game more difficult to play, it is simply due to AI! At higher difficulty, computer defends better because it manage to intercept my passes more often while computer attacks better by having very good vision at passing to player at good position. For PES3, I have played it on PS2 several times at my friend's place before I got the demo. And once I got the demo, I play 5 stars difficult right away and just lost 1 or 2 games so far, though most of the time, I got drew because I am crap at scoring, still need to practice on this! So far, I feel FIFA is more difficult to play, but not sure in the future, i may be able to find a scoring formula just like earlier fifa series, but anyway, in earlier fifa series, I always win after playing for few hours, so FIFA 2004 already improves a lot! Actually, I found that FIFA 2004 requires more techique in defending thanks to the crap defensive AI for my teammate (but the opponent defence AI is very good though), the reason is I found that computer controlled teammates have the tendency to leave the player they are marking and go to the player who is having the ball. And remember that because opponent passing is just so great that they will immediately pass to that unmarked player and thus create a one on one situation to the keeper. It makes me need to switch my players often in order to make sure they all marked the right people.
How about graphics and sound? For graphics, it depends on ur taste, FIFA may have more details faces, but the ligthing effects make those faces look like plastic
! So I will give a draw in graphics. For musics and sound effects, FIFA is better.
So which is better package to buy? It is a tough choice. I will buy both. They are both very good games and I am sure I will enjoy both games for a long time. But if I can only buy one. I probably will go for FIFA 2004 PC version because of its PC fusion feature with TCM2004.