Tonight, the company announced a second round of Windows 7 machines, including multiple multi-touch TouchSmarts. The new all-in-one touch PCs include the 20″ TouchSmart 300, starting at $899, and the 23″ TouchSmart 600, starting at $1049; the company is also introducing a refreshed version of the TouchSmart tx2, a $799 laptop with a flip-around 12.1″ screen. Those systems are all aimed at consumers, but HP is also going after businesses with the TouchSmart 9100, an all-in-one that starts at $1299 and is meant for applications such as kiosks in public places. It’s even launching the HP LD4200tm, a $2799 touch-screen LCD TV meant for use as digital signage.

I reviewed a nicely loaded $1600 configuration of the TouchSmart 600 for PC World– it runs Windows 7 Home Premium 64-bit and has a Core 2 Duo CPU, Blu-Ray, a TV tuner with remote control, a 750GB hard drive, and a lot of other features–basically, it would be a very nice all-in-one PC whether or not it had a touch interface.

But it does do multi-touch, and the most interesting thing about this feature isn’t the hardware aspect, but HP’s software. Windows 7′s support for touch involves making features and functions such as the Start menu, Taskbar, and document scrolling work with a fingertip instead of a mouse. But Microsoft didn’t reinvent Windows to work well with finger-driven input. It didn’t even bundle any applications with the OS that really show off what touch can do.

All of HP’s new TouchSmarts come with an updated version of the alternative interface that the company has bundled with its touch PCs from the start. It’s quite impressive and noticeably improved this time around: You get media playback programs, Hulu and Netflix, Pandora, a Twitter client, a recipe database, and other applications that have actually been written with multi-touch input in mind, with big buttons and support for gestures such as flicking and pinching. The apps now multi-task, too. In short, the TouchSmart really feels like it was designed with touch in mind. This is Windows we’re talking about, so plenty of tasks work far better with a keyboard and mouse; the TouchSmart includes wireless versions of both.

I’m still not convinced that touch is going to become a pervasive part of Windows anytime soon–as I say in the PC World review, it’s a fun luxury rather than an essential new feature. (It’s hard to make a new form of input essential when it’s been grafted onto an interface that worked just fine with the input options it already had.) But HP’s done a nice job of making touch make sense, and the numerous other manufacturers who plan to release touch-capable Windows 7 machines have some catching up to do from the software standpoint.

The TouchSmart 600 and TouchSmart tx2 are scheduled for release next week on October 22nd, Windows 7′s debut day; the TouchSmart 300 will follow on November 1st.

Today, N-trig announced that it had completed a US$24 million fund raising round from investors, including Aurum Ventures, Challenger Ltd., Canaan Partners, Evergreen Venture Partners, and Microsoft. The Wall Street Journal is reporting that Microsoft was the largest investor.

This investment should help ensure that the screens work well with Windows 7 and any other multitouch devices Microsoft might release (touchscreen Zunes, anyone?)  in addition to making the technology more widely available to hardware manufacturers. It makes a lot of sense for Microsoft to be certain that multitouch devices are on the market when it ships Windows 7, because customers will doubtless be looking for the feature.

A friend, who is a not-so-tech savvy lawyer, sent me a text message today expressing his excitement after he read an article about “Windows 7 having a touchscreen.” Customers will be dissatisfied if there are no multitouch PCs ready to buy when Windows 7 ships.

Microsoft needs happy customers in order to maintain its market share and strengthen the Windows brand. Its investment in N-trig is a down payment.