I don't want to erase my Windows 7 but I want to use Ubuntu. Is there an easy way to make a boot-able Ubuntu dvd? I really want to try out Ubuntu on my Windows 7 and having Ubuntu everywhere i go.
Yes, you can create Ubuntu CDs and DVDs. You can download the .iso files here.
You can use any CD or bootable stick for live system testing. On USB sticks you can even even create an area to store changed settings and additionally installed software. But don't forget that using a live system will always be significantly slower than an installed version of the operating system.
If you want to install it alongside Windows, see here for information on dual boot.
yes. you can download ISO and burn it dvd. Boot using the dvd. But as the dvd is readonly, you won't able to save your changes. like downloaded software will get deleted once you reboot.
I suggest using a usb with persistance mode so that you can save your changes.
Many program can confugure your usb for that. One of them is Linux live Usb creater (LILI)
also remember using a os from USB will seriously reduce life span of the usb
At last i will say, you can install ubuntu without deleting windows 7. There are in many tutorial on web. If you need help on that just create a new question.