A Summer to Upgrade.

I have some spare cash to use this summer, I think I am going to put it into my PC; below are my specs:

CPU:
Intel Core 2 Duo E6400 Conroe 2.13GHz (No OCing, Stock HS)

Mobo
ASRock 775Dual-VSTA (Bit of a cheap motherboard, But it had an AGP slot - When I was buying it, I wanted to use my existing Radeon x1600XT card. The mobo has a PCIe x16 slot on it, but it only operates @ 4x)

Ram:
Patriot 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 667 (PC2 5300)

PSU
COOLMAX CP-500T EPS12V 500W (I really like the PSU, looks nice and clean and quite)

Case:
COOLER MASTER Centurion 5 (I bought this mainly for the price, I got it while it has a rebate on it for 40 dollars + shipping - I dont love it, but I dont hate it either. Right now I would like to have a case with more fans for better cooling, and possible a clear side panel.)

HDD
Western Digital Caviar SE WD1600JSRTL 160GB 7200 RPM SATA 3.0Gb/s Hard Drive (Really need to get a bigger one.. Should have originally. ATM I have 20gb free.)

I also have a PCI bay cooler, which does lower the temperature of the inside of my case, but it is kind of loud - I bought a cheap one, but it does the job. I also have a sony DVD RW burner (No Lightscribe)

I have 2 17" LCD monitors

My computer is on 24/7 as a lot of yours are I assume do. I play World of Warcraft on it a lot, In addition I also use Autodesk Revit, Autocad, and Inventor. I also use Solidworks from time to time. 80% of the time I am playing WoW on it though (Yes, Im an addict and proud to admit it ) I usually have iTunes, GAIM XChat, Firefox open, Along with NOD32 and KPF and AVG Anti Spyware running in the background. Probably a few more that I am forgetting to mention.

I dont have may lag problems at the moment, WoW isnt very resourse intensive from what I can tell (Except RAM wise). I usually have WoW open on one screen (Window'd and Max'd) and Firefox/GAIM/iTunes open on the other screen. The only time it lags is if I am in a big area and I switch from FF to iTunes, or attempt to open another program. For the most part it is nice though.


Now.. I have a few decisions to make:

Case - As I said above, I dont love it nor do I hate it. If I did purchase another case it would be an Antec 900 mostlikely. I think I will probably end up modding my case I have not to suit my needs. I would hate to spend 130 on a new case when I can just mod mine for >50g. I really dont care how nice it looks, I really just care about whats inside.

New Monitor - I think that it is time to upgrade to a new monitor, the 17" is nice. But I recently played on a friends computer who has a 21.1" monitor, All I can say is WOW.. The bigger resolution and size of it is amazing. I really think it would make my game play much more exciting. This may lead to another problem though, If I get a 20 or 21 inch monitor (Widescreen) - I am not sure if my Video card (Raedon x1600XT) will be able to handle the 21" and one 17" monitor as well as it is handleing my 2 17" monitors currently. I am guessing that I am going to have to upgrade my graphics card also..Any suggestions if I do?

Other:
I am still using the stock CPU cooler, it is fairly quiet so it doesnt bother me. I am thinking that I might want to upgrade to a better cooler though. Mainly for the fact that my case doesnt really have great airflow in it- The only good thing is on the CM5 case, it has a wind funnel that goes right over the Heatsink which is great. Im not sure if I really need to upgrade though, I suppose it wouldnt hurt. Speedfan clocks my CPU at about 40 degrees idle (on both cores) - Seems a little warm to me, Im not sure how much a *decent* cooler will bring my temps down.

Another few things I want to get are a new PCI bay cooler, a more quiet, better made, one. Also a new 110mm and 80mm fan (Red LEDs) for the two standard fans for my CM5, I am also going to put another 110mm intake below my DVDRom and DVD RW drives, I think the increased air flow will help to improve the coolness. I honestly dont think the 80mm fan is really doing a whole lot - I have three hard drives right in front of it(one 160gb sata, and 2 80gb SATA, so airflow is minimal down there.

Just looking for opinions or suggestions on what I should do. Currently I think I am just going to mod my CM5 to suit my needs. Im just not sure about the Monitor and Videocard.

Thanks!