ideally get one of the latest PowerMac G5's with PCIe slots (better and easier to find upgrade parts ) but the aircooled one's , the watercooling can be a bit of a headache if it starts leaking and means often a dead PowerMac as the cooling liquid is very corrosive eating even the case the best case szenario , more often they liquid spills on the logicboard rendering that in a pile of useless plastic's with some chips on
even the fastest dual core 2.3 ghz can be had for under the price of a mini 1.5 ghz intel single core and the G5 2.3 dual core if fitted with the ATI x1900 graphics card will run circles around the intel Mini single core and 1.66core duo (those minis offer same performance as netbooks as they share the same GPU intel GMA 950 shared graphics and the old core duo offers no much more performance then a newer atom dual core processor ) and those G5's are highly upgradeable
the iMac G5's are a bit of a danger , only buy one if the seller can proof it was refurbished and the capacitors had been all replaced, even the ALS and iSight models (the ones with webcam)had some of the bad caps mainly in the PSU , as its not a question of if those bad caps Apple fitted will start leaking , the question is when
my prefered PPC Mac actually is the eMac (get the ones with USB2.0)
best of all the 1.42ghz model the top of the line and last PPC Mac sold so its the youngest too from 2005 /2006 , and the most reliable Mac of all times
takes 2GB ram !! and has the best GPU too ATI radeon 9600 with 64mb vram (the others only have the 9200 with 32mb vram, not bad but obvious less performance)),comes often already with DVD rw drive and Airport express (wireless G) as standard it plays all your youtube stuff up to 480p , the overall performance is above netbooks
ok the eMac is not whisper quiet you will always hear one , but as the huge fan (nearly as big as a entire mini ) is running at constant speed its not that bad , after all thats the Mac where you never have to worry about overheating , the heatpipe was overengineered..Apple thought NASA wants to use those eMac's on a mission to the sun i suppose
best thing even the 1.42 ghz models can now be had for under £100 and that is money wisely spend for getting used to OSX
the Mini G4 is a alternative to the eMac's but cost often double the price of the equivalent eMac and can only take 1 GB ram max
all above will run OSX Leopard (the last OS for PPC) , ok i still prefer Tiger
dont worry obout older Apps you need to use , the differences between the new and old software is neglectable for the consumer user and only of interest for Pro's really or does it for example matter to you to use microsoft offce 2004 instead of office 2011 for writing the odd letter or do some spread sheets or if you need to use photoshop cs4 instead of cs5 ...no doesn't for home use and as you dont want to use your Mac as a gaming rig you can happy without regret use PPC Mac's , and there are still games out there that run on PPC too , just a bit older , but not less fun
all of the above still can sync iPhones too
but if you need or want to use snow leopard which is intel only the cheapest are netbooks they often even get sold on ebay already setup as hackintosh running OSX snow leopard , and i would prefere spending £140 on a MSI wind U100 or a Dell mini 10 running happy 10.6.8 snow leopard and all functions work perfect then on a Macbook first generation which have a tendency to blow their logicboards and still cost around above £300 in any condition for one that still works even with a display with some dead lines of pixels
intel Mac's might be able to run newer software but USED they are way way overpriced for what you get in return
just read here a test or review between the MSI wind U100 and a MacBook Air 1.6ghz core2 duo
http://crave.cnet.co.uk/laptops/battle-of-the-breeze-msi-wind-versus-macbook-air-49297991/
there is no relation between price and quality offered in intel Mac's , the only thing that keeps that price so high is: people want you to finance their next new Mac , so i say hands away from intel Mac's once they are no longer covered by Apple care , or they have to be realistically priced like 4-6 year old other PC's...PPC Mac's at least have collectors value , if they would be cars you could say they are youngtimers that can still be used every day