Mint is usually very good indeed at dealing with wireless connections, so it might be worth checking whether anyone on the forums has a solution to that problem. You will need to tell us what kind of machine you are using, and what sort of wi-fi card (or dongle) you are using, and exactly what you have done to try to get the connection to work. For example, does Mint see some connections, but refuses to let you connect Are you trying to access a hidden network?
Almost anything is likely to be less hassle than installing Windows from scratch (and in any case, you refer to an "old windows CD - if it predates XP, I would expect it to have some major difficulties in dealing with wi-fi).
The exact process of booting from a CD depends on the BIOS of your computer (although most of them are set up to boot automatically from a bootable CD). The most common keys for changing the boot order are probably ESC or F2, but there have been all too many exceptions over the years. You need to insert the CD while you are powered up (in Mint is fine). Then shut down. Then hold down the relevant key while pushing the power button. In some special cases (the eeePC range, for example, if you happen to have enabled the so-called "boot-booster") you may have to press the key (F2 in that particular case) repeatedly while powering up in order to get a response. Sorting through the BIOS interface will bring back memories of the 1970s, for those of us who are old enough to have been involved in computing at that time.