The Thunderbird solution requires installing Thunderbird on PC. Thunderbird can import PST files as long as Outlook is installed on the same PC. Once all the mail is in Thundebird, you can use it to export to mbox files, which Apple Mail can read. There are a lot of recent roadblocks to this method though, the big one being if you have a 64bit version of Outlook. Thunderbird is 32bit and Windows won't let 32bit and 64bit software to talk to each other. It also tends to not work if the PSTs had folder structures that were complex and multiple levels deep.
How much mail is in the PST files? If it isn't a lot and you have decent broadband, the easy way might be to sign up for an email account that provides IMAP access, like Gmail. Set it up on Outlook on a PC and in Mail on the new Mac. Open the PSTs in Outlook and then right-click and copy the messages and folders up to the gmail account, IMAP will sync everything down to the Mac. For contacts and calendars, you can use Outlook to export vcard/csv and iCal files. This obviously isn't the fastest method, but I've used it a couple of times for users with less than 5GB of mail and it worked very well and is done in a couple hours usually.
