I order the Crucial memory direct from their site as recommended by so many on this site.
The iMac was ordered early on Sunday morning, and it arrived on Wednesday around lunchtime. The online order tracking is pretty good, and tells you as it passes through the stages. Also, in the UK they ship with UPS, which allows you to see exactly where it is once you get the tracking number, which is pretty cool.
I was sat at work Wednesday morning and could see it was on the van for delivery, so told the wife NOT to leave the house under any condition
I am very impressed with the Refurb purchase, and speaking with Apple support today (network issue - didn't know my Wireless Router should use channel 11 for Apple) the support guy instantly new my name, address, and equipment I have from the phone number i dialed in on. I was very impressed, and have continued to be impressed by Apple since switching from Windows.
Oh, as for the Graphics improvement.... I installed COD4 today, and will NOT be playing it anymore. The Mac is not the best platform for gaming

Xbox360 still has a place in my heart

I'm sure the better graphics will be handy for Video processing stuff of course.