Windows 7: Need Help in backing up OS

I have purchased a new HP Laptop with Windows 7 Home Basic 64bit preinstalled in it. There was only single partition. With the help of some HP tools I was able to create backup DVD's which now contains the initial image of my harddisk. Then, I removed the recovery partition. Now, the problem is that I have created another partition using windows tool in which I keep my essential data. If, ever I have to format the system, and I use the backup DVD's then my data in second partition will be lost as it was just one partition earlier. How do I plan a backup so that my data in second partition remains safe in case I have to reformat the OS partition. I don't want to use imaging softwares, neither do I have any external HDD. I have got windows 7 key written at the back of my lappy. Will it be of any help ?? I just want to be able to reinstall win 7 in the current OS partition using the key as I don't have the original CD. And I don't care about the data in OS partition.

Best to backup to a external HDD.
System Image Recovery
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Restore Backup User and System Files

As I understand it, your essential data is on a hard drive and you have no other place to back it up.

You don't have much choice--you have to get another drive, device, or location of some type--a hard drive, a USB drive, or pay an online service for the storage. You could use DVDs, but I would not.

There are numerous "file by file" backup programs that will work, but you need to think about the location.

And I agree with theog: DVDs are a poor way to backup your operating system.

Ok thanks. I will try to get an external HDD then. But I would like to know whether it is possible to reinstall windows 7 using OEM key which is at the back of my laptop? I din't get any install disks from the manufacturer, so I want to download windows 7 from internet and activate it using the OEM key. Is it possible?

Yes follow these steps: Reinstalling Windows 7

I would have kept the Recovery partition onboard as a more stable way to run Factory Recovery, since the disks can fail. But relying on a Windows 7 backup image is a better way to eventually recovery anyway.
Backup Complete Computer - Create an Image Backup

New HP's also have a minimal recovery which is almost as good as a clean reinstall without the factory bloatware, and I believe you can direct recovery of OS to one partition although you should cue up Recovery to see for sure.

That is exactly what I want. But I removed the Recovery Partition so I am not sure whether the backup dvds I made would be able to install just in one partition, leaving the other ones intact.