I have worked in the corporate world for a decade, and the only things I have seen IBM used for were servers (x86 and Z Series). Not once has someone said, hey let's get some software from IBM. Now we'll get our servers from Lenovo. I hope their excellent industrial design doesn't suffer (as it did a bit in the ThinkPad line).
They bring in close to $30b in revenue each quarter and only a small portion of that is hardware. It's quite possible you do use IBM software and don't know it because you know it as another brand they bought or you work with a competing vendor and really don't have any IBM software. It's also possible you aren't in an enterprise shop.
When you log onto your corporate intranet, you may not realize how much of what you see if powered by IBM. They sell a lot of big software packages that cost gobs of money and are often used across an entire corporation, so perhaps you weren't in the position to make the purchasing decision. For example, tons of companies used Lotus Notes for email (now Connections), there are loads of Websphere Portal software add-ons, and they're really into business process management and collaboration software these days (Facebook and Dropbox and wikis and whatnot across the organization).
