Just been playing around on the configurator.
The high-end Mac Mini (2.5GHz i5 with 6630M) upgraded to 2.7GHz i7 comes out at £700.80 on the HE store. I think that'll be what I'll get. A quad-core would be nice, but as it's a choice between graphics and processor I'm gonna go for graphics.
Apple's memory upgrade price from 4GB to 8GB of £150

is a bit stupid though.. when crucial will sell you an 8GB kit (2x4GB) of 204-pin SODIMM DDR3 PC3-8500 for
£55.19 
.
With regards to hard-drive, I'd
like an SSD, but Apple's upgrade price of £400 is too much for me, and TBH 256GB would be a bit overkill. I'll probably get an Intel 510 120GB (£200)... but we need to see what the iFixit boys reckon of the insides of these new 2011 Minis. If worse comes to the worse I'll pay an Apple Premium Reseller/Authorised Repairer to put it in (I doubt the Apple retail store would!)
I was gonna be all afraid of
Lion's download only... how do we burn it to a DVD and
Mac Mini has no DVD drive... how do I install an OS from disc but
http://www.apple.com/macosx/recovery/ says
"If your Mac problem is a little less common your hard drive has failed or youve installed a hard drive without OS X, for example Internet Recovery takes over automatically. It downloads and starts Lion Recovery directly from Apple servers over a broadband Internet connection. And your Mac has access to the same Lion Recovery features online. Internet Recovery is built into every newly-released Mac starting with the Mac mini and MacBook Air."
My reading of that is that something clever in the BIOS of the Mac will notice that the hard drive installed does not have the recovery partition that Lion makes and will automatically make the recovery partition and download the relevant files to it, and then hitting Command-R will get you into the recovery partition from which you can run Disk Utility or start the Lion download and install.