You can burn it from your friend's PC. Here's how you do it.
Click on Start -> All Programs -> Maintenance.
Tip: An alternative is to execute recdisc from the Run box or a Command Prompt window. If you do that, you can skip to Step 3 below.
Click on the Create a System Repair Disc shortcut.
Choose your optical disc drive from the Drive: drop-down box.
Insert a blank disc in your optical drive.
Note: An empty CD should be large enough for a System Repair Disc. I created a Windows 7 System Repair Disc on a new Windows 7 32-bit installation and it was only 145MB. If you only have a blank DVD or BD available, that's okay too of course.
Click the Create disc button.
Windows 7 will now create the System Repair Disc on the blank disc you inserted in the previous step. No special disc burning software is required.
After the System Repair Disc creation is complete, Windows 7 displays a dialog box that you can close by clicking the Close button.
Click the OK button back on the original Create a system repair disc window that's now showing up on your screen.
Label the disc as "Windows 7 System Repair Disc" and keep it someplace safe.