I had the same scenario as you (64 GB SSD + 750 GB HDD) and I was doing a clean install.
First I moved my old data files from the previous OS drive user profile to similarly named folders on the second drive. For example, I copied C:\Users\Me\Documents to D:\Documents.
Then I used the library feature in Windows 7 to add the data folders to the appropriate libraries. This is easy to do. After booting up the Windows 7 system, I just used Windows Explorer to find the D:\Documents folder. Then I right-clicked D:\Documents and chose "Include In Library" > "Documents".
You can also configure the default save location per library so that programs which access the library will automatically save their files to the second drive. Right click on the library and choose "Properties". When the properties window appears you will see a list of all location included in the library. By default, Windows 7 includes the folder from your profile (C:\Users\Me\Documents) and a folder from the default profile (C:\Users\Public\Documents). You should also see the folder you just added (D:\Documents). Click on D:\Documents and then click the "Set Save Location" button, then click OK.
You can do the same for the "Music", "Pictures" and "Video" libraries. And if you want to really go nuts you can create your own libraries too. For example, I created one called "Software" where I save all my Setup, Installer and ISO files.
Works great for me. My files are on the other drive and they are still easy to find. Here's an article with more information: Windows 7 Feature Focus: Libraries