Then seriously, you should consider waiting a short time, and going with the Acer Revo that Totallymaxed is talking about. They cost GBP150 inc VAT and delivery. They have the 9400M nVidia chip in them. You can get it working for 0710, but it might be better to wait for 0810 beta.
As far as HD is concerned.... hmm that depends on what you actually mean by HD. Most people make this mistake, so it is important to understand what HD means in various contexts....
First, HD as in HDTV (DVB, which is what matters for the UK) is simply the resolution - 720p, 1080i (there is no 1080p yet for TV, but that is coming with DVB-T2; 576p is EDTV and 576i is SDTV). None of this says very much at all about the hardware performance required. That is because that is far more dependant on the bit rate and codec used.
Sure, higher resolution means more work to do, but that is generally less important that the bit rate and codec you throw at the video. Most systems, even with low end CPUs, will handle SD, ED and HD TV (upto 720p, and usually 1080i). The codec is just MPEG2, and the bit rates for SDTV (in Australia, dunno about other locations) is about 6Mb/s, HDTV about 12-15Mb/s. Only at the higher of these bit rates are you going to need a high end CPU, as we have no offload to hardware decoding of the nVidia chipsets, yet.... but that is coming soon.
However, if you are talking about high bit rates OR codecs like H264, then you are going to need a very high end CPU until the video offload is available (VDPAU). And BluRay/HDDVD is BOTH high bit rate and H264, so most systems will struggle unless they are kick-arse systems, until the video off load is available. Note: BluRay/HDDVD support in LMCE is very limited at the moment for other reasons as well.
You will often find media files (from various legal sources on the Internet) that are 720p or 1080p, usually H264 in a .mkv file.... NOTE: this is just the resolution, the bit rates of these are still quiet low, and so nothing like the heavy duty load of BluRay even though it is still H264.
The point is 1080p does not automatically equal heavy load, it depends on the codec and bit rate, as those can vary considerably. Whereas you can generally assume that BluRay will mean very heavy load.... so mileage will vary based on these and your CPU until such times as the VDPAU enhancement is integrated.. .at which point you will be able easily to play as high quality bit streams with H264 codecs as you like on an Acer Revo even though it has a very low end CPU.