iMac running low on RAM

My iMac (2008) is currently munching up RAM like a toddler in a candy shop. As I type I only have Safari open and it is showing between 10-16MB of RAM available. I have run Etre Check which has given me a full report but I have absolutely no idea what I'm meant to be looking for or how I'm meant to resolve it. I'm hoping there is a good Samaritan out there who is able to point me in the right direction. In general my machine works well and I have just cleaned up the hard drive where there were some link errors but I can't understand where all my RAM is going?

Here are the Etrecheck results:

EtreCheck version: 1.9.15 (52)

Report generated 18 September 2014 12:33:03 BST

Hardware Information: ?

iMac (20-inch, Early 2008) (Verified)

iMac - model: iMac8,1

1 2.66 GHz Intel Core 2 Duo CPU: 2 cores

4 GB RAM

Video Information: ?

ATI Radeon HD 2600 Pro - VRAM: 256 MB

iMac 1680 x 1050

System Software: ?

OS X 10.9.4 (13E28) - Uptime: 0 days 0:48:16

Disk Information: ?

ST3500418ASQ disk0 : (500.11 GB)

S.M.A.R.T. Status: Verified

EFI (disk0s1) <not mounted>: 209.7 MB

Macintosh HD (disk0s2) / [Startup]: 406.3 GB (7.25 GB free) (Low!)

Recovery HD (disk0s3) <not mounted>: 650 MB

Untitled (disk0s4) /Volumes/Untitled: 92.95 GB (44.55 GB free)

USB Information: ?

PIXART USB OPTICAL MOUSE

Microsoft Comfort Curve Keyboard 3000

SanDisk Cruzer Blade 16.01 GB

S.M.A.R.T. Status: Verified

ACS CRUSER (disk1s1) /Volumes/ACS CRUSER: 16.01 GB (14.27 GB free)

Apple Inc. Built-in iSight

Western Digital Elements 10B8 2 TB

S.M.A.R.T. Status: Verified

EFI (disk2s1) <not mounted>: 209.7 MB

WD ADRIAN (disk2s2) /Volumes/WD ADRIAN: 2 TB (1.54 TB free)

Apple Inc. BRCM2046 Hub

Apple Inc. Bluetooth USB Host Controller

Apple Computer, Inc. IR Receiver

Configuration files: ?

/etc/sysctl.conf - Exists

Gatekeeper: ?

Mac App Store and identified developers

Kernel Extensions: ?

[not loaded] com.freecom.driver.BoulderScsi (1.0.0d1) Support

[not loaded] com.paceap.kext.pacesupport.leopard (5.7.2) Support

[not loaded] com.paceap.kext.pacesupport.master (5.7.2) Support

[not loaded] com.paceap.kext.pacesupport.panther (5.7.2) Support

[loaded] com.paceap.kext.pacesupport.snowleopard (5.7.2) Support

[not loaded] com.paceap.kext.pacesupport.tiger (5.7.2) Support

[not loaded] com.wacom.kext.pentablet (5.0.8) Support

Startup Items: ?

PACESupport: Path: /Library/StartupItems/PACESupport

Launch Daemons: ?

[loaded] com.adobe.fpsaud.plist Support

[loaded] com.adobe.versioncueCS4.plist Support

[running] com.edb.launchd.postgresql-8.4.plist Support

[loaded] com.microsoft.office.licensing.helper.plist Support

[loaded] PACESupport.plist Support

Launch Agents: ?

[not loaded] com.adobe.AAM.Updater-1.0.plist Support

[loaded] com.adobe.CS4ServiceManager.plist Support

[loaded] com.hp.help.tocgenerator.plist Support

[running] com.wacom.pentablet.plist Support

User Launch Agents: ?

[loaded] com.adobe.ARM.[...].plist Support

[failed] com.apple.CSConfigDotMacCert-@me.com-SharedServices.Agent.plist

[loaded] com.divx.agent.postinstall.plist Support

[failed] com.zeobit.MacKeeper.Helper.plist Support

User Login Items: ?

AdobeResourceSynchronizer

Dropbox

HPEventHandler

Internet Plug-ins: ?

OVSHelper: Version: 1.1 Support

Default Browser: Version: 537 - SDK 10.9

Flip4Mac WMV Plugin: Version: 2.4.4.2 Support

Unity Web Player: Version: UnityPlayer version 3.5.5f2 - SDK 10.6 Support

AdobeAAMDetect: Version: AdobeAAMDetect 1.0.0.0 - SDK 10.6 Support

FlashPlayer-10.6: Version: 15.0.0.152 - SDK 10.6 Support

AdobePDFViewerNPAPI: Version: 10.1.10 Support

DivXBrowserPlugin: Version: 2.2 Support

Flash Player: Version: 15.0.0.152 - SDK 10.6 Support

QuickTime Plugin: Version: 7.7.3

iPhotoPhotocast: Version: 7.0

SharePointBrowserPlugin: Version: 14.4.1 - SDK 10.6 Support

AdobePDFViewer: Version: 10.1.10 Support

Silverlight: Version: 5.1.10411.0 - SDK 10.6 Support

JavaAppletPlugin: Version: 14.9.0 - SDK 10.7 Check version

Safari Extensions: ?

DivXHTML5

Find & Remind

Audio Plug-ins: ?

BluetoothAudioPlugIn: Version: 1.0 - SDK 10.9

AirPlay: Version: 2.0 - SDK 10.9

AppleAVBAudio: Version: 203.2 - SDK 10.9

iSightAudio: Version: 7.7.3 - SDK 10.9

iTunes Plug-ins: ?

Quartz Composer Visualizer: Version: 1.4 - SDK 10.9

User Internet Plug-ins ?

BrowserPlus_2.9.8: Version: 2.9.8 Support

UploadManager: Version: Unknown

ContentManager: Version: Unknown

RocketEngine: Version: Unknown

3rd Party Preference Panes: ?

Adobe Version Cue CS4 Support

BrowserPlus Support

DivX Support

Flash Player Support

Flip4Mac WMV Support

PenTablet Support

Time Machine: ?

Skip System Files: NO

Auto backup: YES

Volumes being backed up:

Macintosh HD: Disk size: 378.40 GB Disk used: 371.64 GB

Destinations:

Original Doc Archive [Local] (Last used)

Total size: 549.96 GB

Total number of backups: 22

Oldest backup: 2014-02-16 00:12:34 +0000

Last backup: 2014-08-04 14:29:16 +0000

Size of backup disk: Too small

Backup size 549.96 GB < (Disk used 371.64 GB X 3)

Time Machine details may not be accurate.

All volumes being backed up may not be listed.

Top Processes by CPU: ?

2% WindowServer

1% Dropbox

1% fontd

0% Memory Clean

0% aosnotifyd

Top Processes by Memory: ?

262 MB Safari

115 MB com.apple.IconServicesAgent

115 MB com.apple.WebKit.WebContent

78 MB Dock

74 MB Dropbox

Virtual Memory Information: ?

1.15 GB Free RAM

1.75 GB Active RAM

614 MB Inactive RAM

501 MB Wired RAM

372 MB Page-ins

0 B Page-outs