If you plan on changing your case then plan on buying a new mb and operating system as well. Not only are the panel connection "Dell Only" but the operating system is tied to the mb as well. Seriously, if you plan on doing gaming then your looking at a new system as the one you have is limited for many of the reasons you've stated. If your replacing the mb, op system, graphics and case your already most of the the way to a complete system. Sorry but the joy of owning Dell is being locked into their limited upgrade path. Dell would rather sell you a new system then allow you to upgrade your way out of a new purchase.
The 540s uses an OEM variant of a Foxconn micro-ATX mainboard. The sockets for the front panel connections are standard, and a third-party CPU heat sink will work provided that the Intel push-pins are replaced with screws such as those supplied with the Thermalright 775 Bolt-thru kit. The power supply is standard TFX, not proprietary, micro-ATX or ATX. (400-watt TFX power supplies are occasionally available on eBay.) And, the OS product key will activate with non-Dell hardware although a call to the Microsoft 1-800 line may be necessary. Been there, done that.
I own a 540s refurb that I bought in stripped down form from eBay and pieced back together with mostly third-party parts. The only proprietary parts I needed were the shoulder screws for the drives and the Flex-bay bracket I used for the third-party card reader.
So, you're saying the cases I posted should be alright since the front panels are standard too? Where do I get the proprietary screws you mentioned? Could I just borrow the ones in my 540s Slim case?
It really upsets me its this confusing to simply take all the parts out of my PC and put them into a new case. Just to get a new PSU/Graphics Card. I'm not a technical genius when it comes to PCs but I've done this before...and it was never this confusing. My fault for not researching the buy I guess.
If you could recommend me a good 500-550w PSU, a case big enough(and easy enough) to transfer my Dell parts to them and roomy enough for a NVIDIA GTX 460...it would be greatly appreciated. Thanks.
Yes, you can use the parts in a standard case. The mainboard's front audio and USB headers are standard. I'm not 100% sure about the pin block for the on-off switch, HD activity light, etc but they are connected via a standard 10-pin plug; you may have to switch them around ... or not.
You won't need the proprietary screws if you are using a new case.The proprietary parts I bought were needed to use third-party parts in my 540s case, not move the 540s parts to an aftermarket case.
BTW you won't be able to re-use the CPU heatsink unless you buy a bolt-through kit, like I used with a retail Foxconn board. I would recommend using an aftermarket fan like a Rosewill that has the standard Intel push-pins.
And, finally, If you are moving the parts into a new case, you won't need to reactivate Windows.