I think the blu-ray rips should be alright actually... the acer aspire revo has an NVIDIA ION Graphics chip, which according to nvidia support full 1080p content and directx 10. Just make sure you get the right codecs for the operating system of your choice to ensure smooth playback and it'll be fine. To be honest, I have an old graphics card (geforce 7300gs), which isn't even directx 10 compatible, but still plays blu-ray rips perfectly fine!
also, are you going for a 32 bit system or a 64 bit system? because 32 bit systems hardly have any support for triple and quad cores anyway, and can only have 3gbs of RAM, so the triple core cpu and 4gb of ram is a little uneccesary. However I'm guessing he chose 4gb because of the dual channel advantages it can receive. saying that, the 667MHz should be at least 800MHz to prepare for future installments of a 64 bit installment. no sense getting a lower speed when the higher speed models are almost the same price.
Can I mention, I think you should try and get some ethernet plug adaptors instead of a wireless network as wired connection are much safer, and 100% stable. Ethernet plug adaptors have gotten A LOT cheaper over the last few years, so getting them are becoming much more plausible. I have several pairs of ethernet adaptors in my house because I prefer the stability in the network. ~This is not entirely neccasary though! If you have a good wireless connection going, then utilise it all ya want; I'm just trying to give you all the options
Oh and as for the whole linux vs windows thing... I own several PCs all with Windows XP, and Vista. But I strip them both down of all the crap to just give me the operating system. If you're good with PCs, Vista will work perfectly fine, but since you say you're a MAC user for 12+ years, you may actually find linux more suitable. However, I really think you should give Vista a try first, especiially since you'll be getting it pre-installed. Just make sure you've got a decent anti-virus (such as NOD32) and a good registry cleaner (such as Regcure). I've never had any problems with windows... but then again, I am an IT tech.
If you do decide to go for the Acer Aspire, give us a good review of it once you've got it? I'd love to hear how it all turns out for you! ~I plan to get the same PC for my parents someday.