Here is the story(its short)

 I just bought a new computer with the following specs:

• CPU: Intel E2160 1.8ghz@ 3.0ghz
• MOBO:Gygabite EP35-DS3R
  
• RAM: OCZ Gold DDR800@832mhz 2x1gig
  
• SATA1: Hitachi 80gig
  
• SATA2: Seagate 250gig
  
• SATA3: Maxtor 500gig
• SATA4: Hitachi 500gig
  
• SATA5: Western Digital 500gig
  
• SATA6: DvD-RW-DL
• VIDEO: Gygabite Geforce 7200gs Pci-E
  
• FAN: 4 x 120mm

The power supply that is running all this is an Antec Earthwatts 430watts.

 My questions is simple, if I replace the Geforce 7200gs with an ATI X1950XT 256meg, would it be too much to ask.

 I'm assuming that it would be asking a lot, but maybe someone can prove me wrong!

 Thank you!

It should be able to handle it. But that definitely is a lot of hardware....You'll be pushing it pretty damn hard. Do you plan to overclock also? If so..100% won't be enough.

BTW..Why a x1950XT?...Are you getting it from a friend or something? Are you buying it? If so how much?...If you are trying to upgrade to a new card...the x1950XT isn't bad...it'll perform lower then a 3850...but if you bump up the AA/Af...it should be similar...but the x1950XT Would take more power for sure....Just drop a reply with what you're in terms of this card...

Well I can get it brand new for 90$. Since I only want to play very seldomly, games like C&C 3 or the Half-Life 2 game variant(CS:Source/TF2/portal) as well as some older games I don't want that much power. I don't plan on overclocking the card.

I have to assume its a guess, since as you said its pushing the boundaries.

I know its an aging card, but for 90$(that is all included, tax and all) I think its a good value. Any thoughts? 

For 90 bucks including tax/shipping..That's not bad of a deal at all. When I stated in regarding to overclocking..I was talking about your cpu...Are you oc'ing your allendale?

Choice is yours really..It should work if you're not overclocking your CPU...But it is indeed pushing it. Do keep in mind though, as a psu ages, it's output ability begins to degrade...But it should be fine, although as stated, pushing it. If your rig does bluescreen, or freeze/restart/artifact on 3d application launches..you'll know you don't have enough juice...BUT...what resolution are you playing in? 256 mb is very low..only suited for 1280x1024 and below. If you plan to play in 1650x1050+...you'll want to get a 512 mb card.

I know prety much everything there is to know about ram vs resolution.

Again I want to do very light gaming. I do have an aging Dell 2405fpw and in the past I`ve owned an ATI 1900xt 512mb, which was great at that time. Seriously the only reason I plan on changing from my 7200gs is because that card cannot play any game at any resolution(which I know when I bought it). Since then I decided I wanted to do light gaming, albeit the limited PSU capabilities.

 My allendale is overclocked to 3ghz right now and its running very well and cool as well.

 I guess I'll try my friends aging X850xt for fun and see whats the outcome, if the system can use that card, the 1950xt should be equally functionnal(assumption I'll try to test in a near future hehe)

 A x850xt takes less power than a x1950xt if I remember correctly..If you're oc'ed...with a x1950XT..AND those hard drives and 4 fans, sorry budy but I doubt you'll have enough juice for it. Also...with that monitor...You will probably run into less frame rates when compared to the extra memory of a x1950xtx...but it still shouldn't be unbareable based on your gaming selection.

what is your CPu voltage atm? 

This is all you need. http://www.extreme.outervision.com/psucalculator.jsp   

I'd personally get a higher wattage psu, especially because of all of those hds. 

I may be posting too late, but you will need a more powerful PSU, undoubtably.  The X1950XT is a pretty big power hog.

Well, unless your PSU has excellent amps on the 12v rail.  As in 30 or more.  But even that may not be quite enough since you have so many drives.

 Make sure you purchase a quality PSU, not just the cheapest thing you can get.

 Preferably 600 watt or more, with at least 40 amps on th 12 volt rail.

600W might be a BIT more than he needs -- 500W would be enough I think. As everyone else has said -- DON'T GO FOR CHEAP!! GET QUALITY as PSUs are an extremely vital part of your system. Keep in mind that if a PSU fails probably 1/2 the time it will take a handful of your other pretty components down with it should it surge before dying.

Corsair/Seasonic are very good, FSP (Fortron), PC Power and Cooling, and OCZ all make good PSUs

Again as everyone else says its important to look at the amperage on the 12V rail(s) -- adding them up for at least 25A is probably about the minimum here (granted you cannot just add them up for a true efficiency across the rail....but just for argument's sake).

Recap: 500W minimum....good brand...good powerflow through 12V....saavy?