Hi all.
Well Microsoft have come to the party gain with Windows 7 proffesional upgrade 32 or 64 bit for $49.95 Australian dollars Scratch that they hiked the price up to $119 a copy now.
TSK TSK
http://www.microsoft.com/student/discounts/itsnotcheating/default.aspx
I have grabbed it and i am downloading it now.
By far the cheapest way to get windows 7.
Have at it 
As an aside this is how i created a bootable win7 disk.
just grab the file from digital river(3 gig odd) run it it expands abunch of files and a setup windows opens close that then find these files
- folder and files list expanded
in the expanded setup folder is the windows installation files.
then follow this guide from basically point 4 down.
this is what i did and i have a bootable disk.
i am about to test it installing over an old winxp 32 bit so i will need to format a fresh.
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Addition
To clear a few things up What is the difference between what I can purchase from the online store versus in a retail store?
There is no difference between the Windows 7 software you will install from the online store versus in retail stores. However, if you need to perform a custom (clean) install on your PC, we recommend you purchase the back-up DVD.
From
http://store.digitalriver.com/store/msshau/ContentTheme/pbPage.Windows_7_FAQ
Also
Terms
http://www.microsoft.com/student/discounts/itsnotcheating/terms.aspx
Not sure if this is mentioned anywhere but there is a windows 7 usb/dvd tool to whack the iso on.
http://www.microsoftstore.com.au/shop/Help/Windows-7-USB-DVD-Download-Tool
good for netbooks(i knwo the other methods are fine but always nice to have choices )
ok didn’t work with my iso…
another point to make.
you can use the 32 bit code for the 64 bit disk so you can purchase 2 copies on one account(sometimes 3 if they screw up ) you can do a clean install on a fresh hardrive using various methods.
http://www.winsupersite.com/win7/clean_install_upgrade_media.asp
1 2 or 3 will work usually (i have done a clean install formatting the drives then installing and by not using the key initially it installed and allowed me to add the key and activate, did this twice)
now legally it is a bit of hmmm as the EULA clearly states that you must have a qualifying OS for upgrade and that OS will be disabled and not usable after the upgrade, (so if you do a double install then you disable the os you are using :p) seems that the windows 7 RC is a valid upgrade path as this did work (using a clean install though) also seems any copies of windows will allow it to install (windows xp nt4 win98 msdnna copies etc) so if you have an ol win 98 hard drive around throw it in and see if it allows an install.
So it is up to you in regards to above…just because it works doesn’t make it right