Let me start off by saying-
Welcome to the Forums!
I have one thing to say about the beginning of this thread-
We have a lot of people who simply post up and ask what they should get without giving us any info at all....
As you can imagine, this gets tiresome by the 150th time you have responded to it. Sometimes someone will respond in a manner that is...less than conducive to helping or making someone feel welcomed in the forums. Stick around for a while and you too will find yourself in the same situation, eventually.
The list Guderian posted up is an excellent starting point:
we now know that you need blocks for an AMD Barton 2500 and ATI 9800 Pro, you have plenty of room in the case and are willing to spend a decent chunk of change for the system.
We also know that you have some skill in the sarcasm department.
Careful with that one, as it can alienate people if they don't realize you are joking in the future: the "smilies" can be of help there......
Back on topic,
Does your motherboard have the mounting holes around the cpu socket?
If not then you are a bit more limited on block choice, although there are at least a few good ones that you can use- Swiftech stuff comes to mind.
GPU block- no clue there- I don't do much with video water cooling.
Pumps: many options depending on how you want to go- 12v, AC hobby/pond pumps (most common) like Eheim, Mag, Hydor, etc.
There are also some big-money pumps that are even better, but you will eat up half or more of your budget perhaps- Iwaki is one example of these.
Then there are some fairly standard parts- 1/2" ID Clearflex or Tygon tube; heater core for a radiator- either a single 120mm fan size (1 fan per side) like the Chevette cores, or a dual 120mm fan sized core. I think the most common of those are late 70s Bonnevilles or something....some GM car, anyway.
There are other radiator options but they all cost more and vary from slightly less performance to slightly more- I think heater cores are the only option unless you have a strange case/goal in mind.
As for exactly WHICH components to get- there are too many that are too close to being equal to say that THIS is better than THAT- just get THIS one. Take another look through some of the stickies and forums, look on some of the water cooling vendor sites (DTek, Swiftech, DD and such) and see what looks good to you.
When you list the stuff you are thinking about getting, or at least looking at, you will tend to get more help.