That's why I'm partial to services like YouSendIt, which let you send big files without all the hassles. To use the service, you head to the site, enter the name(s) and e-mail address(es) of your recipient(s), and then choose the file you want to send it. After it uploads, the recipients get an e-mail containing a link that downloads the file.
Of course, that's a lot more steps than just attaching a file to an e-mail--which is why I'm now using YouSendIt's Outlook plug-in. This freebie lets me leverage the service without using the Web site or even leaving Outlook: I can "Attach by YouSendIt" any file I would normally attach to an e-mail, or have the plug-in automatically kick in for files larger than a designated size (say, 5MB).
There's also a new plug-in for Microsoft Office that works much the same way, but operates within the confines of Word, Excel, and PowerPoint. Neat stuff.
YouSendIt isn't the only game in town: There are loads of services that match, or even exceed, its capabilities. (Drop.io comes to mind.) But I've always had good luck with YouSendIt, and the plug-ins are icing on the cake. You do have to register in order to use them, but in return you get a free YouSendIt Lite account that lets you send files as large as 100MB.