Sweet! Without question, a worthy upgrade. You will be in heaven... Are you going from XP or Vista to Windows 7? If so, I can do Windows 7 in my sleep, so just holler if you need help. Inland is even better...
Because this computer will be just as though you built it yourself, it will come with none of the bloatware on a branded computer. For instance, if you used Outlook Express or Windows Live, you will have to download Windows Live Essentials for email, Messenger and a ton of other free extras. If you have a paid subscription to an antivirus program, you should be able to transfer it. Otherwise, download and install one of the excellent free ones such as Microsoft Security Essentials or Avast. Unlike branded computers, you will get all your original driver and operating system disks too.
If life gives you lemons, make lemonade. If life gives you tomatoes, make Bloody Marys.