The increasing use of Commercial off the Shelf (COTS) products in the Swedish defence could cause increased problems with radiated interference against colocated wireless communication systems. This is due to that COTS-products generally radiate significantly higher levels of unintentional electromagnetic radiation than corresponding military specified products do. It is therefore important to have updated knowledge of typical interference levels in order to perform vulnerability analyses when COTS-products and wireless communication systems are colocated in different scenarios. Since personal computer (PC) is a type of system which is commonly used in defence applications the work has been focused on interference from such systems. In this document investigations of interference spectrum from modern PCs are reported. From these results an intersystem-interference analysis has been performed for colocation between COTS and two chosen system types of defence interest; the army combat radio Ra 180/480 and GPS (Global Positioning System). Mesurements of radiated interference have been made by cooperation with the Swedish Research and Testing Institute (SP). The analysis shows that colocation between GPS and typical PCs can cause severe interference problems on GPS function at colocation distances up to about 90 m. Colocation between typical PCs and systems of Ra 180/480 type shows severe interference problems at colocation distances up to about 30 m.