My current computer is a refurb from two years ago.  It has AGP graphics still.  My card is a GeForce 6800GS 256MB.  I'm running XP with 2.5GB of memory.
 
I've recently been running into problems in World of Warcraft, that lead me to believe I need to upgrade the graphics card I have or just buy a new machine.  In general, I run WoW fine, but for 25 man raids I'm having problems if I have to have the graphics dialed up, which is necessary for certain endgame fights.
 
So, my questions:  
 
Is there a better AGP card that would be worth getting that would give me a large boost in performance?
 
If not, I would probably buy a machine from a Dell or HP or some such.  Would the cards they have available in their midrange machines be much of an upgrade graphically?  For HP it looks like it would be: 512 MB GeForce 8600GT.  For Dell: 256MB GeForce 8600 GTS or 256MB Radeon ATI HD 2600 XT.
 
Thanks for any help.

I don't think it's a good idea to upgrade your pc. It's too old.
 
If you want to buy a pc, the Dell with the 8600GTS has the fastest video card out of the 3.

2.5 gig of memory? Are you running oddball sticks, so it's not running in dual channel mode? There are better AGP cards, but lets see the rest of your specs and see if indeed it will be worth spending the money for a newer card.

His upgrade options are going to be limited by both the fact that it's AGP and the fact that he probably has a low Wattage Dell Power Supply that may or not have another power connector. This means that he might need a NEW Power Supply and a NEW graphics card.  
Personally, I don't see the point unless you're not going to be able to get a new system for 2+ years.
The 8600GTS and 256MB Radeon 2600XT aren't very big steps up from the 6800GS except for 3.0 and DX10 (8600~7600~6800), which I'm assuming isn't really important to you. The fact it's AGP probably means your processor is also old and prone to bottlenecking your other parts, so getting a higher card isn't worth it either.
All in all, an $800 rig built today could crush your POS, so don't bother upgrading.

 
Actually it would be a big upgrade if he plays any of the recent games with shader heavy like COD4, Unreal 3, Crysis, etc.
 
To: OP
 
You should just upgrade your whole computer.  Don't poor money into an old system.

I'd recommend building your own machine if you have the know how or want to gain the know how. You'll have a much better performing machine and you can tailor it to your exact specifications. Plus, you'll save a lot of money for the same specs.  
 
Also, those machines from Dell,HP, ect. have a lot of bloatware installed with 30-day trials. When I bought my laptop just recently, I did a fresh format and reinstall because of all the crap they had put on the machine.
 
If you need any help choosing parts/building your computer, you have all of us here on the forum to help you.

Thanks for all the replies.  I'm not sure what kind of power supply I have, but it is most likely as Loser777 guessed, something low wattage from Dell.  The machine has two Pentium 4 2.8 GHz CPUs.
 
I've never built an entire system, but I'll consider it.  The biggest advantage to me of building it at home would be that I could use XP instead of Vista.  Most of the prebuilt places require you get Vista on new machines.

Dual Pentium 4's? Now that IS interesting.
I am thinking that a new GPU could indeed breath some gaming life back into that rig for a while.  
I would guess that the machine has a beefier power supply than you or we are lead to believe. What exact model is it, your PC that is....

Are you sure it isn't a Pentium 4 using HT? Is it actually 2 Physical CPUs?

 
I haven't taken it apart and examined the CPU, no.  In Device Manager there are two entries that both say Intel(R) Pentium(R) 4 CPU 2.80 GHz.  It is a Dell Dimension 4600.

Its a single core, dell or anyother would never make a  2CPU P4.. unless u got a Pentium Dual Core which then would make sense

Okay, armed with that info, and if you want to play modern games or increase your gaming power, you need to just buy a new system.  
 
The Dell Dimension 4600 made the March '07 issue of PC World.....it was #10 on the list of "The 10 Worst PC's of All Time"
 
It's a single Hyperthreaded CPU, the power supply is a very low grade 250watt. Many of the 4600's with the Hyperthreaded CPU's simply died within weeks of shipment when they were new.  
 
Dude, you got a Dell, ...........sorry about that, but what more can we say.
Now we understand why it is a refurb, they had a lot of these come back to fix.
 

Thank you, that's exactly what I came here to find out.
 
I suppose now I'll look into whether it would be worth it to me to build one, or if I'll buy something from HP or Dell.

 
What problems are those?

The sentence after the one you quoted in my original post answered this.  To be more specific, my frames per second drops a lot when I dial Spell Detail to full, which is necessary for some fights (Vashj is the problem for me currently.)

if you think you're system is worth keeping, get the hard to find ATi 3850 AGP card.  I'd recommend a full system upgrade though.

Anything more than a Radeon x1950GT will be massively bottlenecked by your CPU

I remember playing that game and the funny thing was the 40 Man BWL raids... When Vael was first released.. man did that kill Video cards.
 
My 6800 GT barely kept up.

Plunky, you can build a pretty mean machine for WoW for $500.00.  I was about to buy a base Dell XPS for $999 dollars but decided to build my own machine and I ended up saving a ton and having a system with better performance.   I was having a smiliar problem to your own, bad fps in raids.  Heres what I picked up (about 2 weeks ago)
 
Core 2 Duo E2200 - $90
Gigabyte P-35 Mobo - $90
Western Digital 160 gig - $49
Case - $50
PSU 500watt - $50
2 Gigs of DDR 800mhz RAM - $50
Optical Drive - $30
Video Card: GeForce 7900 GS 256meg - $79 off e-bay, fantastic card.
 
I can run WoW max everything 1680x1050 at constant 60 FPS.  Just make sure you don't skim on the PSU.  I had bought a case that came with a PSU but the SATA rails were bad so I had to chunk it.

Thanks for the input Doc.  I'm leaning toward trying my hand at putting something together.