Exactly how much space will Win 7 take on HDD

Assuming a new HDD, clean install, formatted to NTFS.
Does anyone know how much space will be taken up on the drive with just the operating system and any drivers that might be needed.
No programs, no data, just the O/S and drivers.

For 7 Pro and for 7 ultimate.

Also assuming everything else will always be put onto a second drive what size drive do you think you could effectively get away with using? again for either Pro or Ultimate.

well i'm currently installing 7 pro at the moment onto a 40Gb drive, i pretty sure it takes up 9 or 10 gigs

i just checked and 7 pro 32bit needs 5.7gb of free space to just fit so i'd recommend at least a 40gb drive. BTW home basic and up use the same amount of space.

Thanks, Reason I'm asking is I need to decide (from several options) which way I want to go with my upgrade.

ok, what are the other options??

In no particular order.
1/ Format my 32gig Velociraptor drive and just put 7 ultimate on it. (cheapest option)
2/ Get new larger HDD, probably WD caviar black and partition it to put on Win 7 + XP Pro + Linux mint 9.
3/ Get larger Velociraptor and put win7 + XP Pro on it.
4/ Get SSD and put just Win 7 on it. (don't think partitioning a SSD would be a good idea)

Cool.. the cheapest opt windows 7 wise is to download the iso and then buy the key for it. download >> Windows 7 ISO – Official Direct Download Links

Would it be cheaper then those prices I quoted for OEM disks?

There also seems to be a size difference between 32bit and 64bit installs. I can't remember the numbers but I definately take more space on my 64bit Ultimate than I did in 32 bit.

Microsoft recommends 15Gigs for 32bit and 20Gigs for 64bit...