Some tech shops continue to sink while others swim ahead against the slow-spending current.

Networking and security gearmakers are running strong as businesses build and safeguard their expanding networks, but PC and server sales look to be on the losing end of the ongoing corporate budget squeeze, according to a second-half 2008 spending forecast report by RBC.

Outfits such as Cisco (CSCO) and Juniper (JNPR) stand to benefit from whatever modest gains come along in IT spending. And PC shops such as Hewlett-Packard (HPQ) and Dell (DELL) as well as software giant Microsoft (MSFT) will feel more of the pinch as tight-fisted procurement officers continue to lay off the new computers for awhile more.

RBC analysts surveyed “2,049 leading-edge corporate IT buyers” about their spending plans for the remainder of the year. The results showed that spending will likely remain soft and tied to the overall economy. The good news is that there seems to be no significant decrease in spending ahead, says RBC.

“We should continue to expect difficulty in getting deals signed as companies still appear hesitant to spend on IT products and services: 56% of respondents claim their company has a red/yellow light when it comes to spending on IT, the highest level in over four years.” RBC says in its report Wednesday.

Some bright spots amid the gloom include Research in Motion (RIMM), which RBC expects to gain another 5 percentage points and walk away with 82% of the mobile e-mail business market this year.

And Apple (AAPL) continues to have a hot hand among the corporate crowd, says RBC. Unlike the slide in PC sales, Macs are taking more share in the office. RBC expects Apple to build 3.5 percentage points of overall computer market share in 2008, up from the 2.9-percentage-point gain last year. RBC says Apple will close in on 10% marketshare in business computers this year, up from 7.2% in 2007.