Looking for video card for a Dell GX280 MT

Hey guys. For the past few days I've been researching graphics cards, because I've been desperately wanting to upgrade, but I'm still at a loss on what to get. I have a Dell GX280 Mini Tower computer that my brother gave me a while back.

This is my first post, so I guess I'll go by the book.

APPROXIMATE PURCHASE DATE: None, really. Matter of fact, I was planning on asking for a new card for Christmas. Yeah, I know, it's a couple months away, but it's never too late to get started on that list, right?

BUDGET RANGE: Since someone else may be buying it for me, I want to keep the price low, preferably under $200. And, even if I were to buy it myself, I'd still be budget-conscious. I don't feel that I need a $600 card to have a decent gaming experience.

USAGE FROM MOST TO LEAST IMPORTANT: I'm not exactly a hardcore gamer (I play FPS games mostly, and I play online only if there's a server running a zombie mod), but I want a card that can tolerate games running on the Source engine or Unreal Engine 3 (such as Borderlands) at high settings. I also make video mashups from time to time, but I'm not a die-hard video editor, so I don't need any extra oomph for that.

CURRENT GPU AND POWER SUPPLY: VisionTek Radeon HD 4350, and a Dell 305W power supply (Model # N305P-00). I know I'm going to have to upgrade my power supply, but I've discovered that Dell power supplies for some of the Optiplex systems aren't standard (the PSU's plug to the motherboard is not ATX, or something of that sort), so I fear my options are limited. I was thinking of something along the lines of a Corsair 450W/500W power supply, such as this:

Corsair CMPSU-450VX 450-Watt VX Series 80 Plus Certified Power Supply compatible with Core i7 and Core i5
http://www.amazon.com/Corsair-CMPS [...] =de_a_smtd

And then combining that with a Dell-To-ATX adapter, though I don't know if the Corsair will even fit in my case.

I've also read that having a power supply with a single 12V rail outputting about 20-30A is good enough for a mid-range computer, but I got that from some forum post I came across thanks to Google, so I don't know if that's accurate or not. I also don't know what it even means.

OTHER RELEVANT SYSTEM SPECS:
- Dell Optiplex GX280 Mini Tower Computer
- Intel Pentium 4 520 (Prescott) 2.8 GHZ Processor
- Dell Motherboard, model # 0C5706 (can't really find the exact motherboard name), Intel 915G Express chipset
- 4 sticks of 512 GB DDR2 SDRAM, totaling 2GB; my computer can hold 4GB max
- Fan-based cooling system (non-liquid based, of course)
- Seagate 1TB 7200 RPM hard drive
- Dell wide-screen monitor
- Windows 7

PREFERRED WEBSITE(S) FOR PARTS: Newegg, Amazon.

PARTS PREFERENCES: I don't really practice brand loyalty, but the last three cards I've had were all Radeon, so I've still got my eye on Radeon cards. In general, however, I wish for a card that just works regardless of brand.

OVERCLOCKING: No

SLI/CROSSFIRE: No

MONITOR RESOLUTION: My maximum monitor resolution is 1680x1050, though when I'm playing games I usually play at 1024x760 or some other resolution that doesn't make the screen look stretched.

ADDITIONAL COMMENTS: Given where the PCI-E x16 port on my motherboard is located, the video card takes up the top-most slot on the case, so I can't use a double-slot card.

I've been considering this one:

XFX HD-577X-ZMF3 Radeon HD 5770 1GB 128-bit DDR5 PCI Express 2.1 x16 CrossFireX Support Video Card with Eyefinity
http://www.newegg.com/Product/Prod [...] _-14150501

...since my options are limited, given the above fact.

If anyone could offer me some advice or recommend anything, that would be great. Thanks.

PS: Is the data on Passmark's Video Card Benchmarking site (http://www.videocardbenchmark.net/) accurate? Because I've been using that to compare video card models (as well as reading reviews and checking out the specs, of course)

that card would run your games at high settings no prob in your resolution
i would suggest getting a new psu for that graphics card and the corsair 450w will work fine with it...
i know its a christmas gift and you want to keep price as low as possible but better than 5770 i would suggest the 6850
its around 180 or 190...
would be more future proof and would work a lot better if you plan on going for a higher resolution on your monitor...

Sorry about the late reply. Meant to check on the post but forgot about it.

I'm not in the market for a HD68xx card (tomate2 suggested that, not me), and I've considered a Radeon HD5670 (this one by XFX, or a smaller model) rather than the HD5770 card due to the fact that it (presumably) doesn't require a lot of power and thus I won't have to worry too much about my PSU. Still deciding on that one, though. As I said before, I generally run on low settings regardless, and I'm not looking to play Crysis at 60 FPS.

In any case, I know I'm sacrificing graphical power, since the computer's so old. I'll have to upgrade eventually.

I had considered replacing the CPU (and found a few on Ebay), but I don't know if the upgrade would be worth it.

I had also looked around for Dell-compatible PSUs, and the ones I've found seem more expensive than similar PSUs on the market. Maybe I'm looking in the wrong spot.

As for ram, yeah, I know the max is 4 GB, but I don't have the 64-bit version of Windows 7 to utilize that much memory, so I'm kinda out of luck there.

Then again, if I'm going to upgrade in the future, modifying what I have right now just seems like a waste.

Anyway, thanks for the reply. I'll keep looking around.