The 'GeForce 6600' is only half as fast as the 'GeForce 6600 GT' btw - I never recommend the 6600 'non GT', nor the 6800 'non GT/GS' models, to gamers, for these reasons.
Since a GeForce 6600 (non GT) and GeForce 6150 perform fairly closely, especially in mediumish detail, may as well pocket any extra money, and put it towards 'at least' a GeForce 6800 GS, if not a GeForce 7600 GT/GS or Radeon X1800 GTO in the no to distant future.
Additional: The board costs no extra, and sports a PCIe x16 slot, so if 'they crave maximum detail'
there is no financial risk at all, just spend the extra and install a better video card.
Only downside is the wait for the new card to arrive, if, they decide the onboard isn't enough. Very often they do, then end up sending the 6600 (non GT) back, as the boost in performance is not what they expected.
Sure the Ultra models are not much better than the GT/GS, but the ones that lack any extention, or use XT (nVidia only), LE, SE, etc are all impaired cards. Onboard GeForce 6150 is just as good for what he wants.
Of course the main exception is that ATI use 'XT' to designate 'better than normal', nVidia just use XT on their lower end cards to try and get people to associate XT = bad..... a rather crude (and ineffective, as people are not that observant in general) market tactic. ATI use Pro, XL, XT, XT PE, XTX, etc to designate 'better than the OEM basic model', which is sometimes only half the power of the Pro/XL varient. (Hey, if people are buying a full 'brand name' PC they generally don't know video card model numbers off the top of their heads.... in detail)
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Anyways, back to the core subject at hand.....
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Either spend the extra US$70 (or whatever) to get a GeForce 6800 GS, or GeForce 6600 GT, or Radeon X800 XL, whatever takes your fancy,... or just use onboard GeForce 6150 (performance will suffice fine in World of Warcraft, and Counter-Strike: Source on mid detail)
until you can afford a 'significantly' better video card, likely next generation GeForce 7600 GT/GS not to far down the track, esp since you can go well under your US$800 budget if it is mostly an upgrade and you are resourceful.
If you were not resourceful, you wouldn't be trying to build a US$500 - US$800 PC.... at least that is the way I see it.
Being resourceful, and saving for the 'big fish' at the 'right momment' (hint Octoberish any year, and Aprilish any year) will, within 3-9 months depending what you are after, get you a system you don't even think you can afford, let alone one 'your rich friend' can afford.... if you get my gist.
8)
I did the same thing ages ago. Radeon 9000 Pro (far better than 9000 plain, just like the 6600 GT kicks the crap out of the 6600 'plain vanilla'), and held out to get a Radeon 9700 Pro not much longer afterwards. Ultimately the system was better than I was expecting.... instead of settling for a sub par card.
The difference between the GeForce 6150 onboard (with decent dual-channel memory) and the GeForce 6600 (non-GT) is not that significant.
If he is 'addicted to WoW' then he might as well benefit from that addiction
, and when / if he/she gets tried of WoW and wants more 'pretty' in Counter-Strike: Source, and beyond upgrade to a GeForce 7600 GT for all the new stuff they are going to be doing in the HL2 / Source engine come 2007.
Heck, just look at the stuff Half-Life 2: Lost Coast is suggesting for decent performance, and the features in the new CS: Source and DoD maps (which can be turned off btw, and would need to be off on a 6600, even the 6600 GT, for decent performance anyway....).
The GeForce 6150 has access to the memory controller on the Athlon 64, which despite not being 256 bit x 1.2 GHz GDDR3 memory (not that the 6600 is offering anywhere near that anyway
), is still a fairly decent memory controller.
Anyway, the system I suggested is only hitting his minimum wall budget, he could just add a GeForce 6800 GS or GeForce 7600 GT to it now, and still be fairly close to budget.
History: I didn't get to my current system (see rig) without scrounging every last dollar on my earlier rigs. I certainly didn't spend money on 'sub par' parts when the increase over a 'basically free' part was minimal.... and then just save for the big fish while having 'acceptable' performance in the mean time.
A little bit if patience, and selling my old systems before they devalued, combined with my above notes is what got me a 4-processor core Opteron system today. 8) (bling, bling).
Heck, my 1st
real PC was a Celeron 466 (MMX only), clocked to 583/83, PC100 at 83 using damn fast timings, with a 8 MB Vanta (nVidia Riva TNT2 core basically), as 8 MB video memory then was heaps, AGP could use system memory for the low res textures of the time, and it kicked the crap out of every Voodoo SLI system at the time for the same, if not lower, cost).
That 8 MB TNT2 lasted me ages and only cost AU$70. (US$50 or so at the time). Then moved to GeForce 4 MX-400 (32 MB), early, when the card was quite good, then Radeon 9000 Pro, then 9700 Pro, then 3 x 9800 Pro (multiple PCs), then Radeon X800 XL. <-- They where my main tactical buying choices, bear in mind I'd sell stuff if it devalued too much, well before it was worth 'almost nothing' and use that money in the 'next project'.
To re-iterate: My signature system is where those 'tactical buying choices' got me today. 8)
UPDATE: ... and back then TNT2 Vanta 8 MB was the best choice as a starting block, because boards with GeForce 6150's 'for free' did not exist back then. Onboard video back then really was 'the dogs arse'. (As the board is so cost effective the video costs nothing bar the 64-128 MB drop in available system memory, which with 1 or 2 GB of decent PC3200 DDR-SDRAM is not going to hurt) .
But yes, onboard video, except in 'rare' cases, usually does suck in performance.