Cheat Engine

[korby]

However I'll be more specific this time.

I want to play games like CoD5, L4D, Fallout 3 with good speeds. I also do some photoshopping, [for school] but not professionally. I do not download anything on this computer, I have my 1998 piece of crap for music and movies. I have an XP key, but will probably be upgrading to vista's successor when it comes out in January.

I don't know much about the whole core 2 duo vs quad core argument, so help on that would be nice too.

Budget is $1000.
I've already got a razer mouse and a logitech keyboard, so I don't need those. I've got a bass system for my computer, but my speakers are crappy. I don't even think I need speakers though, because I use a razer headset.

What type of screen would you recommend for a gaming computer? Is it the size that matters?
I've got a $250 dell flatscreen. I think it's pretty good.

I'm also clueless on a case. I'd like one that's black with blue LED lights.

Not sure on a cooling system either. Is liquid cooling really worth the extra $100?

[Karakawe]

I don't want to turn this into another dual-core vs quad-core thread, since there are a number of people on the forum who will swear by quad-core computing, but I'll make it brief. It looks like you're into gaming: Now, while a COUPLE games (like Crysis) take advantage of quad-core processors, most modern games only use two cores. Having a higher clock on two cores is generally better for gaming than having a lower clock on four cores.
That being said, I recommend the Intel Core 2 Duo E8400 (as I have in the past) for your build. The E8500 and E8600 only have .5/1 multiplier up on it, not necessarily worth the extra cash. To go with the CPU, get a P45 chipset motherboard: I'd choose the Asus P5Q PRO, although others swear by the Gigabyte P45 alternative.
The monitor really doesn't matter unless you were to go all-out on it. I like my 22" inch screens and 16:10 ratio, but it's mostly preference. For a video card, get a Radeon HD 4850 or a 4870 (budget allowing). That'll be plenty for the games you mentioned and upcoming games.
For a case, go to Newegg and look around there based on reviews. I'm sure you'll find something you like. Note that many are larger than OEM cases, if space is an issue, check the dimensions of the chassis in Specs on newegg.
Now, for the CPU cooling: A $100 dollar system probably won't get you a very good liquid cooling system. I recommend you go with a great air-cooler over a crappy liquid cooler, which might risk damage to your system. Most of the best air coolers are around 45-50 dollars. I recommend an Ultra 120, a Tuniq Tower, or Thermaltake Big Typhoon (the new one). There's a link floating around here somewhere I had been giving out comparing the leaders, but I don't have it at hand. Again, go by review on newegg if in doubt.

[undeadkillers]

If you really want fast things popping up your monitor, get one with less than 5ms response time, why is that? In gaming, Every ms or second counts.

[kls85]

[Imitazion]

Your request is kinda like mine, and I got to this build.
The rate is in DKK(Danish Crowns), but I will be editing when i get the DKK recalculated to USD.

[Zarr]

I'm not going to go into the whole "dual core vs quad core debate", but to put it simply, two cores at a higher speed is typically better than 4 cores at a lower speed at the time being, recent games are, however, taking more advantage of 4 cores. Dual core processors are typically better now, but quad core processors will be better soon.
I suggest a Q6600 or a E8400, depending on whether you want an quad or dual core processor.

As for the mobo, the generally accepted best mobo for the price at the time being are the Asus P5Q Pro and the Gigabyte GA-EP45-DS3L, the gigabyte board being better if you do plan to overclock and the asus board being better if you don't.

I suggest a decent Antec, Corsair or PCP&C PSU, as those seem to be popular these days. This (Antec) is a well designed PSU @ 550W with 3 12 volt rails from a well respected company, good buy for the price. This is also good for a PCP&C PSU. I can't recommend a Corsair PSU, but I've heard good things about them.

As for the GPU, I suggest this or this, the latter being cheaper but somewhat weaker.

RAM: This or this. DDR2 RAM is going up in price now, apparently, thanks to DDR3 starting to become a standard.

HDD: This if you want a 500GB HDD or this if you want a 1TB HDD.

If you plan on overclocking it may be a good idea to get this and this.

Any 20 buck DVDRW SATA drive should work, just get the cheapest thing you can find. This would be fine.

As for the case, Antec 900s are a bit pricey but look nice and have outstanding air flow. Of course you could get something nice and shiny like this, but it doesn't have as great of airflow.

If you need a monitor, get something like this.

The cheapest options listed total out to $685 while the most expensive options listed total out to $934, without a monitor.

To answer your question on liquid cooling, it's a waste of money unless you feel like ridiculously overclocking your shit.