max105, check out the threads on the video forum, for '2D' image quality (clarity, stability etc of image in both 2D and 3D) GF4TI truely are right up there with Rad8500LE and both are a lot closer to the Matrox Parhelia512 that you might think. See the last paragraph for more info on gfx cards.
budgieboo the whole industry speeds up year by year so unless you spend a bit of cash on your PC every 6-12months then you will find your kit devalues and dates REALLY quick. Essentially when thinking of a new PC you need to think of its likely uses, budget and longevity. It is the last point which is often the most difficult to cater for, but essentially you want to buy near the top of the line, ebough so your compnents will last but don't devalue too quickly, and of course you need to ensure the interface/standard will still work with the newer componenets when the time comes to upgrade. So to put it simply, you can upgrade to a Duron1.3ghz (very fast for how much it costs) as this is effectively a DuronXP1500+ (that's before you o/c), the advantage of this is cost effectiveness and the ability to add at least an AthlonXP2200+ (double check the SktA mnobo can take one) at a later date, should be very cheap in 12 months. Another option is to buy an AthlonXP1800+ (best price/perf at the mo) and again you will be able to put at least an XP2200+ in there (again double check mobo) at a later date. However Skt478 is very new, whereas SktA is nearing (only nearing) the end of its road, so you could get a Celeron1.7ghz which gives perf about even to a Duron1.3ghz (yes it's true) but will enable the later addition of at least a P4B 2.53ghz and anything up to that in 12 months or so when the prices have fallen dramaticly (always check the mobo can take these CPUs before purchase). So then your final option is to buy a P4A or P4B on Skt478, P4A 1.8ghz are excellent value for money if you o/c, they often easily reach the 533FSB and 2.4ghz CPU giving IDENTICAL perf to a true P4B 2.4ghz on a 533FSB. If you go P4 be sure to get the Skt478 512k P4A/B CPUs which use the new Northwood core. So that's just considering the CPU!

As for the gfx card, GF4TI4200-128MB is definitely the best price (and longevity) per pound at the moment. The Rad8500LE is very good for its price, but the AA perf sucks, the '2D' image quality is no longer exceptional so all you really get is good 3D perf and very good TVout. Matters are made worse by the oem (vs retail) and non-ATI 'powered' (vs true ATI 'built') which are clocked lower, use cheaper RAM AND often lose '2D' image quality, not only that but with the introduction of the inferior Rad9000 & 9000pro the Rad8500 cards sound even worse to the average consumer, not good when you come to sell it on at a later date. The new nVidia cards are due Nov/Dec but since they will NOT use the GF5 name it helps the GF4 cards to be an even better long term buy. If you only have $90 to spend the GF3 and particularly Rad8500 (rem retail, true ATI and 128MB versions) cards are excellent value and still kick it in 3D perf, but for around $150 the GF4TI4200-128MB offers pretty much the best of everything at the moment and that's before you factor in it's massive o/c'ing potential, 4200 cards either reach 4400 (275/550) or 4600 (300/650) speeds!